Send Orders for Reprints to Reprints@benthamscience.net Household Size and Structure in Iran: 1976-2006

In addition to significant political changes, Iran has experienced a multitude of demographic and economic changes during the last four decades (1976-2006). First, there have been somewhat dramatic changes in marriage and reproduction during this period, with a sharp lowering of fertility to replacement level, an expansion of a strong rural public health program that has increased child survival, increase in age of marriage for both males and females, and an increase in the divorce rate. These changes took place in the context of structural changes in the society, with an increase in urbanization from below 40 percent in 1976 to 68 percent in 2006 and a marked transference in the economy from an agricultural base to manufacturing and service. This paper reports on the analysis of this household transition in Iran during the 1976-2006 period in the context of other changes experienced in this period. We find that despite significant fertility transition along with other demographic and social structural changes, which are expected to lead to conjugal family patterns, as of 2006, a large proportion of households in Iran continue to have five or more members and there has been very modest decline in the share of extended households. It is not clear if this situation is due to the selectivity in continuity of large and extended co-residential households or the result of housing pressure particularly in urban areas.


Background
This paper utilizes data from Iranian censuses to examine the changes in composition and size of households in Iran from 1976 to 2006 in relation to transformations in the Iranian society, economic structure, and urbanization in the context of the relevant theories.Specifically, we examine the impact of demographic and socio-economic changes which have emerged during the 1976-2006 period in the size and composition of households.These changes include decline in mortality and fertility, war migration and urbanization, female educational attainment, and significant shift and share in the economy from a predominantly agriculture to a highly service oriented structure.
Recently, Abbasi-Shavazi and McDonald provided a comprehensive review of studies of family change in the Islamic Republic of Iran [1].From this review, it is clear that one of the less examined areas of family change in the literature is change in household size and composition.Specifically, it seems that, while other aspects of family such as childbearing have been studied intensively, the demography of households is less studied.This situation is not unique to the study of families in Iran.In his study of household size and composition in developing countries, Bongaarts states that "demographers have neglected the *Address correspondence to this author at the Department of Sociology, Fayetteville State University, Fayetteville, NC 28301, USA; Tel: 910-672-2927; Fax: 910-672-1378; E-mail: aaghajanian@uncfsu.eduquantitative dimensions of the size, composition, and change in household and their consequences [2]."

Theoretical Framework
De Vos and Palloni have attempted to fill the gap in the demography of households by developing hypothetical models [3].Their modeling is intended to complement the data collected in censuses and surveys pertaining to households and kin groups -information that by its very nature is limited in regard to the number and complex interrelationships of variables that surely must contribute to an understanding of these issues.Theoretical modeling, on the other hand, can point to potentially important variables and make assumptions about how they might relate to household structure and size.De Vos and Palloni propose a variety of models incorporating diverse independent variables such as socioeconomic conditions, demographic factors, kinship rules of household formation and dissolution, and availability of kin.They also point to the importance of the relationships amongst these variables.
As pointed out by De Vos and Palloni the use of extant data, from censuses and surveys, necessarily limits the variables that can be legitimately included in an attempt to understand household processes.Specifically, the behaviors of concern that are focused upon -in the case of the present study family size and structure -cannot be fully explained by demographic or socioeconomic or other easily quantifiable data, nor do they occur in a vacuum.These behaviors represent individual and family processes that have taken place within the context of a given culture and the values that existed within that culture.Further, they represent individual and couple decision making to the degree that decisions can be made.For example, decisions about childrearing and spacing essentially reflect non-decision making when the culture does not support individual choice and/or there are no available resources that permit individuals or couples to become decision makers.In addition, individual perceptions of opportunities for such behaviors as marital formation and dissolution, changes in head of household status, education, migration, and family size and spacing are as important as the actual existence of these opportunities.
Despite such concerns, descriptive data collected from censuses and surveys can provide indications of changes in individual and family behaviors over time, and these changes can be considered in the light of changes in other family related variables and also in relation to cultural changes and opportunities that have taken place over time and that thus reflect changes in the society as a whole.It is from this perspective that the present study assesses the changes reported in census data concerning household size and structure over an extended period of time.
Within the framework of the theory of family change, alterations in household composition and transition to nuclear family type happen as societies modernize [2,4,5].In largely rural traditional societies, families are more often of an extended type, either horizontally or vertically, than they are in modern industrialized societies in which the independent nuclear family predominates [2].As societies develop, extended households tend to be replaced by nuclear or conjugal households consisting of husband, wife, and children [4].
In demographic terms this convergence happens through changes in the proximate determinants which operate between the social and economic structure of the society and the size and structure of the household.These proximate factors include but are not limited to age of marriage, nuptiality pattern, fertility, adoption, divorce, widowhood, and voluntary or forced migration.Not all of these factors operate in all societies and many of them are regulated and maintained by what is referred to as "idealized family morality" in each society [6].In most cases the source of this morality is religion [7].The established family ethos supported by the society's institutions -particularly religious institutions -embraces various components of the family institution.This is particularly important in relation to gender expectation and household division of labor.In the patriarchal and religious based family morality environment, the reproductive role of women is highly embraced and sanctioned.Hence early marriage and marriage within group are encouraged; domestic roles for women are normally expected to support a large family size; and decision making is within the periphery of extended households with elder males making the important decisions.
Given the idealized family morality of each society, change in household composition requires not only socialstructural transformation as precursor but also moral support and authority.The degree to which idealized family morality tolerates change in any of the components (proximate determinants) varies across time and across societies.As a result of the interaction of "idealized morality" and socialstructural and legal changes, the expectation is that change in different aspects of family will be slow, selective, and cultural-context specific in each society [8,9].

Existing Literature
Our descriptive analysis and interpretation are built on the existing research literature on this topic in the Iranian society.Azdarmaki and Bahar provided a historical and cultural context for the institution of family and family change through Iranian history [10].They discuss the role of politics and religion in shaping and guiding the family as an uninterrupted and strong institution in Iran.They also refer to some of the emotional strains on households as a result of such changes as increasing age of marriage and increase in the incidence of divorce.In discussing family type and the change in family structure, they state that the direction of changes is not from "extensive to nuclear."However, they do not address this issue empirically.
The state of family change during the demographic transition in Iran is presented in a paper by Sarai in the context of globalization and expansion of internet communication in Iran.Sarai focuses on the transition of Iranian society and economy from an agricultural system with family as a unit of production and procreation to the contemporary society with regional variation in the economic system accompanied by more diverse family types [11].He states that, due to the variation in the economic organization and the diversity in the level of integration in globalization, a variety of family types can be observed in Iran.These include: extended families, semi-extended families, and nuclear families with intensive interaction with non-nuclear members.As a longstanding sociologist and observer of the Iranian society, he states that the extended family is declining and different types of nuclear families are emerging.However, he does not offer any data beyond his observation.Indirect evidence about the persistence of the extended family is presented in papers by Givens and Hirschman [12].These researchers report steadiness in the incidence of consanguineous marriages.Historically, these marriages are based on family arrangement and extensive involvement of the members of the extended households.
The existing literature suggests that some of the characteristics of conjugal family relations are emerging in Iran.The conjugal family is composed of the parents and their children with strong emphasis on independence from the larger extended household.On the other hand, there is anecdotal and indirect evidence suggesting that extended household patterns and influence continue.The analysis of census data from 1976 to 2006 is expected to shed some light on these ambiguities.
In understanding the individual and family changes which have molded family size and structure during the period under consideration, we must review the socialstructural transformation in Iran during the same period.Modernization in Iran essentially commenced in the first quarter of the 20 th century with the establishment of a manufacturing sector and expansion of the transportation network of roads and railways [13].With the influx of oil revenue during the 1960s and 1970s, Iran underwent a huge transformation of the economy by establishing consumer goods manufacturing units and importing consumer goods that were not assembled domestically [14].This pattern of modernization and westernization stimulated rural to urban migration and the need for importing food staples for a growing population.This latter furthered the depletion of population from rural villages by reducing the efficiency of subsistence agriculture as it faced competition with imported cheap food staples such as wheat and rice [15].
The shifting in economic sectors in Iran has intensified since 1976 and it has moved the economy away from traditional agricultural production with a great majority of the population in subsistence household production.The Iranian economy has been fueled by revenue from high oil prices and this has unquestionably allowed the development of a large industrial sector and support of a large service sector during recent decades.According to the 2006 census, almost 50 percent of the labor force in Iran was in the service sector.The manufacturing sector had 32 percent of the labor force and agriculture had only 23 percent of the labor force [16].
During the first part of the 20 th century the rate of urbanization in Iran was slow.According to the1966 census, about 35 percent of the population lived in urban areas and only the national capital had a population of more than one million.By 1986, about 54 percent of the population lived in urban areas and 28 percent lived in cities with a population of 250,000 or more.In the 20-year period between 1986 and 2006, the percentage of the population living in cities of 250,000 or more increased from 28 percent to 48 percent; by 2006, 68 percent of the population lived in urban areas [17,18].
Urban crowding has increased with the growth of medium size cities -those with populations between one million and 2.5 million.About 14 percent of the urban population lived in such cities in 2006 as compared to 5.5 percent in 1986 [16].Accordingly, the number of such cities has increased from 1 to 4 but the number of people living in these cities has increased by 350 percent over the period.
Along with the high rate of urbanization, the economic shift, and the increase in the oil revenue, the adoption of modern communications -in particular the use of mass media and technology, predominantly computers and the internet -has accelerated.Through the tremendous increase in access to satellite TV and mobile telephones, by all classes and in all regions, the exposure to Western ideals has been pervasive.These exposures have been strong forces in strengthening the foundations of conjugal family systems with an emphasis on individualism and self-actualization.In addition, Westernization has become an increasingly powerful force in shaking the Iranian idealized family morality and freeing its grip on proximate determinants of household size and composition.
A sharp fertility transition since 1986, lowering of fertility to replacement level, played a major role in reducing household size in Iran.Several researchers have considered the trajectory of fertility decline in Iran in great depth [9,19].While the Iranian population experienced a slight fertility transition, particularly in urban areas, during the 1970s, the gradual transition slowed down during the 1979-1985 period.By 1986 the fertility transition restarted and then accelerated with revival of a family planning program in 1989; specifically, the total fertility rate dropped from 6.23 in 1986 to 2.51 in 1996, a decline of about 60 percent in only one decade.By 2006, total fertility in Iran had declined to 1.88, below replacement level.The Iranian fertility transition was swift and across rural and urban areas.In many cases, the areas with a strong agricultural economic base had the fastest rate of fertility decline.The bulk of fertility decline during the 1990s happened within marriage.
Increase in age of marriage for both men and women but particularly for women should be considered influential in relation to household size.The average age of marriage for females increased from around 22 in 1976 to 28 in 2006.The percentage of never-married women age 35 and higher increased 217 percent between 1991 and 2006.Such findings support the assumption that the Iranian idealized family morality has eased its grip on young women, as young adult women continue to live in their parents' households and expand their access to higher education [1,20].
Traditionally, family morality strongly precluded divorce in Iran [21].Despite the continued strong social stigma against divorce, the divorce and marriage registration data show that divorce has been increasing in Iran during the last three decades.The divorce rate increased from 87.6 per 1,000 marriages in 1991, to 121 per 1, 000 marriages in 2006, an increase of 37 percent [16].Unless they remarry and move to the household of their husbands, the Iranian divorced women live in their parents' household, particularly if they are young.It should be noted that the rate of remarriage for Iranian divorced women is much lower than the rate for divorced men.If, for some reason, divorced women cannot join the household of the parents, the next option is to join the household of a brother.Hence, the increase in divorce rate is expected to affect both the size of the household and the rate of household extension.In addition, to the extent that divorced women set up their own independent households, the rise in the divorce rate contributes to the increase in the share of female-headed households.
Other factors functioning as proximate determinants of household size in Iran are decline in infant mortality and increase in widowhood.Infant mortality was very high in Iran in the 1970s [22,23].Local and national surveys documented a high rate of 112 per 1000 live births.Through the 1980s and more effectively during the 1990s and beyond, infant mortality and child mortality declined through policies leading to improvement of health care resources and developmental activities in small towns and rural areas.By 2006, infant mortality had declined to 26.6 per 1000 live births resulting in a higher level of child survival.The reduction in infant and child mortality could mean larger household sizes; however, reduced fertility could lead to smaller household size.
From 1980 to 1988 Iran was engaged in war with Iraq, her neighbor in the west.The details of this war and its consequences are covered extensively [24][25][26].In general, the war cost Iran heavily in human and material terms [24].A demographic side effect of the eight-year war was an increase in the number of young widows.Religious and nationalistic motivation led to the participation of many young men as volunteer fighters in occupied areas.Many of these young men were either married or hurriedly married before they were deployed.The unofficial estimates of Iranian casualties in the war range from 300,000 to more than a million men.Many of these estimates point to the increase in the number of young widows, many with one or two children.To protect their honor and the reputation of their family, many of the young widows had to return to their parents' households.Hence, many households became extended because of these widows and their children.

Data
The Statistical Center of Iran has conducted national censuses since 1955.The last census of Iran was a five-year interval census conducted in 2011.The data used in this paper are drawn from reports of 1976, 1986, 1996, and 2006 censuses.Since all tabulations are based on population rather than sample the observed differences are statistically significant.Some tables do not include comparable figures from all the four censuses due to lack of published census data.

Households
The Iranian census defines a household as a group of individuals who live in the same dwelling, share household budget, and usually eat together or from the same kitchen.These households are grouped under "Settled Regular Households."A small portion of the population is grouped under "Group Households" and includes individuals living in institutional settings.This definition is centered on residential and budget sharing.However, there are many economic and social interactions that happen among members of the extended family that are not captured by this definition.This is one of the perfect examples of what De Vos and Palloni consider not observable from the census data on households [3].The analysis of household composition in this paper is limited to the residential definition used in the censuses.

Variables
Urban-rural differences are defined in terms of the formal definition by the Statistical Center of Iran.All population living in places with less than 5000 at the time of the census are considered rural unless the place has a mayor.The number of such places is small, such that they make up a trivial share of the urban population.
The rate of urbanization at each census time is the percentage of the population living in urban areas.The definition of these areas is based on the official definition by the Statistical Center of Iran.Accordingly, all population living in places of 5000 or higher or places with less than 5000 population but with a mayor are considered urban.
Economic composition is measured at each census time by the share of the employed labor force in the three major economic sectors of agriculture, services, and manufacturing.

Ethnic Diversity
Iran is an ethnically diverse country.The ethnic identity draws from tribal background, language, culture, and religion [27].Many family issues are affected by regional and ethnic differences [28,29].The ethnic differences, measured by language, religion, and culture, have existed historically but no systematic census of the ethnic groups exists.In his analysis of ethnicity in Iran, Amanolahi identifies 26 ethnic groups based on language and religion.Many of the religious ethnic groups are small in population size [27].For example, the Jewish population counted according to the 2006 census was 9,252 [18].The major language-based ethnic groups with their distinct cultural identity continue to be geographically concentrated in specific provinces [29].For example, Persians live in the provinces in the central plateau of Iran.Kurds and Turks live in the western provinces.The majority of the Baluchi ethnic population live in the eastern province of Sistan-Baluchestan.The Arab ethnic communities live in the southern provinces such as Khuzestan and particularly in the rural areas of these provinces.This geographic concentration has continued despite significant migration from the ethnically concentrated provinces.
To account for ethnic difference, a rate of household extension was constructed to measure ethnic and provincial variation in household extension.The numerator for this rate was the number of extended members in the households in the province.The denominator was the total number of households.The multiplier was 1000.Hence the rate was centered on the number of extended members for each 1,000 households in each province.

Changes in Household Size
There was a slight increase in average household size from 1976 to 1986.However, the marked change in household size happened between 1986 and 2006; the household size decreased from 5.1 to 4.0 persons (Table 1).Most of the decline occurred during the 1996-2006 decade.The amount of decline was the same for rural and urban areas -from 4.9 to 3.9 in urban areas and from 5.5 to 4.4 in rural areas -representing about a 20 percent decline in household size in both areas over the 10 year period.The lower panel of Table 1 reveals that the changes in household size reflect an increase in adult and a decrease in child members.From 1996 to 2006, the average number of adults per household increased, from 2.5 to 2.7 for urban families and from 2.5 to 2.8 for rural families.At the same time, the number of children per household decreased from 2.8 to 1.3; the percent change was essentially the same for urban and rural families (from 2.4 to 1.2 and from 3.0 to 1.6, respectively, for urban and rural households).There are thus about half as many children (age 17 and younger) in 2006 households in all areas as there were in 1996.While these figures cannot predict the possibility that there may be additional children at a later time, they likely reflect the combination of the decrease in fertility and an increase in child survival during this transition period in Iran.
The decline in household size is also reflected in the distribution of households by number of members (Table 2).In 1986, 56 percent of the households had five or more members.By 2006, only 32 percent of total households had this number.The move from five-person households was more dramatic in urban than in rural households, dropping from 52.3 percent to 28.8 percent in urban areas but only from 61.2 percent to 40.2 percent in rural areas, despite the evidence of similar declines in fertility in both urban and rural areas.The major shift in household size distribution is observed for households that have three to four members (increasing from 28.9 to 47.3 percent), although increases are also seen in 1-2 person households as well (from 15 to 20.5 percent for the total sample).Changes in these sizes were similar but slightly less in rural areas (3-4 person households increased by 17.6 in urban areas and by 16.6 in rural areas; 1-2 person households increased by 5.9 percent in urban areas and by 4.4 percent in rural areas).It is clear that changes in the distribution of family sizes are occurring, with a move from larger households of 5 or more members taking place in both urban and rural areas -though less dramatically in rural areas.It should be noted that, despite the changes observed in household size, households of five or more persons remained about one-third of total households in 2006.However, this pattern is not the same in all provinces.Table 3 presents the percent of households with five or more members by province in 2006.There is a relatively wide range of variation in the percent of the households with five and more members; the lowest rate is for Gilan with 23 percent and the highest for Ilam with 49 percent.Although not a perfect correlation, the majority of the provinces populated by a major ethnic group have a higher percentage of households with five or more members.The results presented earlier (Table 1), suggest that over time there has been an increase in the average number of adults per households.If we assume that, on average, two adults in the household are parents, in 2006 there were 0.7 additional adults in the average household.Furthermore, as noted above, one-third of all households had five or more members in 2006.Given the reduced number of children in households at that time, it seems clear that households of five or more have added more adult members.Data reported in Table 4 explain who the added adult members are.Reflecting the increase in age of marriage in Iran, it is perhaps not surprising that these data show an increase over time in the number of young unmarried adults living with their parents.The percentages of never-married men and women by age group presented in Table 4   Source: [17,18,32].

Household Structure
A second explanation for the extra adults and hence a larger household size is the existence of "extended households" in which both relatives and non-relatives (e.g., maids) reside with the nuclear family.Data in Table 5 show the share of extended households among all households in the last three censuses.Comparable data were not available for 1976.According to the 1986 census, rural and urban areas differed very little in terms of the share of extended households.In all areas, about 20 percent of the households were of this type.According to the last two censuses, in 1996 and 2006, the share of extended households has declined a bit in urban areas, from 20.8 percent of the households in 1986 to 15.2 percent in 2006.In rural areas slightly less than 19 percent of the households were extended households in 2006 as compared to 20 percent in 1986.The distribution of extended members of the household by their relation to the head of the household is shown in Table 6.These data are available only for 1976 and 2006.In 2006, in descending order in terms of the largest representation of members other than the nuclear family are: parents of the head (27.1 percent), an equal percentage of grandchildren and siblings of the head (both 23.3 percent), and spouses of married children (21.4 percent).The shares of head's parents and of grandchildren show an increase from 1976, the former by almost 10 percent, while the shares of head's siblings and children's spouses show a decrease from 1976.Other categories represented to only a small degree in 2006 are parents and siblings of the head's spouse (3.1 and 1.8, respectively).There has been a slight increase in the inclusion of spouse's parents but little change in the inclusion of spouse's siblings.Other categories with a small representation include other relatives, maids, and nonrelatives.Source: [17,35].
Table 7 shows some characteristics of the extended household members by three major age groups in 2006.The age groups are those who are 17 and under (children), 18 to 34 (young adults) and 35 and older (older adults and seniors).From the first panel (for ages 17 and younger), it is clear that the majority in this age group (almost 73 percent) are grandchildren.This number combined with the high percentage of daughters-in-law in the 18-34 age group suggests continued persistence of co-residence of young couples and their children with the husband's family.While a large percentage of those in the 18-34 age group (about 40 percent) are siblings of the head, the relatively high percentage of never-married males and females among the extended members age group 18-34, (almost 20 percent for each group) reflects the increase in age of marriage and changes in nuptiality patterns.Among the extended members 35 years and older, more than 75 percent (the largest percentage) are parents of the head, while some 62 percent are widowed females.Relatively small percentages range from more than 8 percent for parents of the head's spouse and unspecified other relatives, to about 5 percent for never married females (status in relation to head and spouse unspecified), to about 2 percent for divorced females.
It is not surprising that a high percentage of those in the 35 and older group are parents of the head, though it might be assumed that this group is made up primarily of widowed mothers, just as there is a large number of widowed females in this group.There are two reasons for anticipating a high frequency of widowed mothers and aunts.First, there remains in Iran a differential life expectancy between men and women; an average of five years in favor of women [22].Second, there also remains a husband-wife age difference.In the past, this difference has been up to an average of seven years.For example, according to the 1966 census the mean age of marriage for women was 18.4 as compared to the mean age of 25 years for men, an average difference of 6.4 years [16].The difference has declined in recent years as the age of marriage for females has increased.In 2006, the mean ages of marriage were 23.2 for women and 26.2 for men, an average difference of 3 years [16].However, this difference continues to contribute to the number of widows -both widowed mothers and widowed aunts -who, as has long been the tradition, live with a son's (or nephew's) household as extended members.Table 8 shows a simple measure of frequency of extended households for Iranian provinces.On the average, there were 160 extended members for each 1,000 households in Iran in 2006.This measure varied among the provinces.Some of these provincial differences might be related to the ethnic diversity and cultural differences across provinces.Overall the rates for extended households in provinces that can be identified with a certain ethnicity are higher as compared to the provinces that are populated by the majority of the population who are Persians.It should be noted that the measure of ethnicity used here is a proxy measure based on residence in province.For example, households living in Kurdistan in 2006 are considered Kurds.However, not all households living in Kurdistan in 2006 were Kurdish.Since an individual level measure of ethnicity is not available, any interpretation of the effect of ethnicity should be considered cautiously.Nevertheless, similar differences found in studies related to other aspects of family change in Iran support the importance of ethnicity and region in the discussion of family type in the present study [29].

Female-Headed Households
A little more than seven percent of households in Iran were headed by women in 1976 (Table 9).This rate declined slightly in 1986.However, it has been increasing since then.Based on the data from the 2006 census, about 10 percent of the heads of households in Iran were women.In terms of numbers, female headship grew by 40 percent during the 1976-86 decade, by 50 percent over the decade of 1986-95, and by 58 percent during 1996-2006.Overall, this represents a relatively sharply increasing trend in female household headship.[18,32,33,34].
Table 10 shows the distribution of female heads by marital status according to the 2006 census.Among the female heads 74 percent were widows.This is not surprising, since widowhood has been a major proximate determinant of female household headship.The second most frequent marital status among female heads was married women.These women may be married to men who have migrated to cities or Persian Gulf countries that are the destination for a large number of temporary labor and business migrations from Iran [30].On the other hand, some of these women might be married to unemployed men or men who have disabilities due to war injury, work injury, or drug addiction.There are no data regarding this group of female household heads.However, they are a very important vulnerable group to be studied for their needs and support.Slightly over five percent of the female heads are divorced women.It seems that, as divorce has been increasing in Iran, a higher proportion of divorced women are heading their own households.It is not clear if this emerging situation is out of necessity or a choice that is made by divorced women.Source: [18].

DISCUSSION
The review of literature on family change in Iran suggests emerging behaviors in the domain of family that reflect the growth of individualism and self-actualization particularly among the young adult population.These behaviors include a remarkable increase in female age of marriage, postponement of birth of first child, and significant decline in total fertility.Yet as of 2006, a large portion of households in Iran continue to have five or more members.It is obvious that a partial explanation of the large share of households with five and more members is the increase in the number of unmarried young adults who are pursuing their education and postponing marriage.The other factor behind the higher share of households with five and more members is persistence of extended households, particularly in the provinces that are populated with major ethnic groups.One explanation for the continuation of this traditional pattern might be choice based on a continuing interest in coresidential family organization.This selective continuity of tradition has been observed in other aspects of family in Iran [1,9].On the other hand, it is possible that, at least in some provinces and particularly in urban areas where the price of housing has increased and young adults cannot afford independent dwelling, an extended household is selected as the best alternative for providing support of the younger generation.Casual observation and systematic research have shown that the price of housing has skyrocketed in Iran particularly in cities [31].Structural changes in societyprincipally the shift from an economy based heavily on agriculture to one dominated by a service-manufacturing emphasis -have resulted in important shifts in demographic behavior, chiefly involving an increasing flow of rural to urban migration.The ever-increasing influx of migrants into cities in search of changing work opportunities makes it likely that both high housing prices and housing shortages will continue.This may force families to choose the coresidence patterns reflected in the data presented in this paper.The published data available for the present research did not allow further investigation of important issues raised here.There is need for data which include comprehensive measures of family structure and composition and also detailed variables related to how these family household constellations evolve and change.

CONCLUSION
In our examination of census data related to household structure in the Iranian society, we observed continuity of tradition and sharp changes simultaneously.We recognize that there are many factors that contribute to the constellation, as noted by De Vos and Palloni [3].While we are considering a particular culture, we assume that, ceteris paribus, the same processes exist across cultures.Our data do not permit us to test relationships or develop causal models.However, we believe the changing patterns in household observed reflect changes in societal values and mores pertaining to family processes including fertility, age of marriage, women's roles, and responsibility for care of the aged.We further believe that changes over time that we have observed follow from pragmatic and modernizing societal changes, such as improved education that affects both men and women and access to resources that permit control over decision making with regard to major family decisions such as family size and housing, including intergenerational coresidence and female headed households.Based on observed changes in Iran, we believe that certain family processes are pervasive.For example, as shown in the data we present and in other data, family size is decreasing across socioeconomic classes in the presence of contraception and the absence of governmental restrictions.However, other family processes, in particular intergenerational co-residence, will more likely reflect both economic pressures and changing societal norms.In particular, we have assumed that the continuing presence of adult children in the family constellation no doubt reflects both normative changes in age of marriage and the cost of maintaining more than one household, We do not propose a specific model nor, as noted (vide supra) can we test many of these assumptions directly with our data.Rather, we believe that the analysis presented here reflects and thus provides further demonstration of societal changes that are observed throughout the recent literature in Iran concerning other family factors, including education, reproduction, migration, and aging.

Table 3 . Percent of Households with Five or More Members by Province, 2006
show relatively large increases in all age ranges, including in ages 35 and above.For those aged 20-24, large increases have happened at each time period; for other age groups the largest changes took place from 1996 to 2006.Overall, the number of nevermarried adult members of the household, increased from 240 per 1,000 households in 1976 to 520 by 2006.

35 Years and Older (Older Adults)
As the percentage of the total in the age group.The percentages do not add up to 100.Source: Calculated by the author from the 2006 census, 2-percent sample file. *

Table 8 . Rate of Extended Households Among Households in Provinces in Iran, 2006
*Provinces populated by a major ethnic group.

Table 9 . Number and Rate of Change for Women Headed Households in Iran
Source: Iran Statistical Center