This work, based on census data and survey results, argues that the apparent trend toward nuclear household forms in urban areas of Algeria after independence represented in fact not a convergence to a "modern" or "western" family structure but a temporary phase in the adjustment of migrant families to their new living conditions in the cities. Census data from the years 1948-87 indicate that the tendency toward nuclear households evident from 1954-66 did not continue thereafter. Since the 1970s, there has been an increase in the number of families per household, and the number has tended to stabilize at about the same level as in 1948. Increasing urbanization, contrary to expectations, has not caused a decline in extended families. Comparison of the distribution of household types in 1966, 1977, and 1983 shows that the differences between rural and urban proportions of each type of household declined regularly after 1966. During the entire period, Algeria's urban population increased primarily because of a massive influx of rural migrants. Data from a 1975-76 retrospective survey of urban household structures of migrants and nonmigrants conducted by the Algerian Association for Demographic, Economic, and Social Research indicated that less than 4% of nonmigrant vs. 7% of migrant households contained a single person. The proportion of nuclear households was about the same for migrants and nonmigrants of the same age and almost independent of the time of migration. The relative importance of extended households containing parents and their married children increased with the duration of the stay in the city. The general process of household composition revealed by the longitudinal study from the most recent to the most distant time periods corresponded to a structure of transformation of migrant families. The newest arrivals tended to live in single-person or nuclear households. After 10-15 years in the city, differences in household structure in similar age groups declined between rural migrants, migrants from other cities, and natives. In the years after 1966, the relative contribution of families of new migrants to urban growth tended to decline because of the already large size of the urban population, and consequently the tendency of new migrants to live in nuclear households had less weight in the overall structure of urban households.