This paper is an attempt to study the current size and structure of family according to different socio-demographic and economic characteristics of the households in India and its states. Data are obtained from the National Family Health Survey conducted in 1998–99 which covered a representative sample from 26 states in the country. Results suggest that the proportion of nuclear family households in 1998-99 increased relatively in both urban (9 per cent) and rural areas (12 per cent) as compared to that in 1981. The mean family household size in India is 5.24 and it varies by the type of family and the demographic development of the state. This paper tests several socio-demographic hypotheses posed in the context of changing family structure and indicates that caste alone does not determine the joint family system. Rather, the jointness in a family depends on the standard of living and the agricultural land owning status of households in the country.