This study identifies the socioeconomic characterisitics of immigrants in Nepal, their fertility, and the incidence of family planning. These characterisitics are contrasted with the receiving or nonmigrant population and inferences drawn regarding the probable social and demographic impact immigrants may have on the "receiving" population. Demographic surveys were conducted annually from 1975 through 1978 in the Hills and Terai by the research and evaluation unit of the Family Planning/Maternal Child Health (FR/MCH) Project. In each of these geographic areas, all districts were matched on a set of social and demographic characteristics. 2 districts were then selected from each area on the basis of their similarity to each other. The sample design for all districts involved selection of panchayats (a political unit roughly equivalent to a country) and their wards (villages) on the basis of a procedure which refers to a selection of units based upon probabilities proportional to size of the population of the units. Currently married women aged 15-44 in all households of the secondary sampling units, i.e., wards, were interviewed. Both migrant women and their husbands had a higher level of educational attainment than nonmigrant women and their husbands. Indian migrants had higher proportions in the largest landholding groups than nonmigrant and lower proportions who are landless. The differential was maintained among Indians who had lived in the Terai for 10 years or less as well as 11 years or more. This finding was particularly striking since Indian migrants make up 25% of the sample. Current marital fertility (as measured by age specific and total fertility rates) was highest among Indian migrants, but cumulative fertility or past reproductive performance (as measured by the mean number of children ever-born) was highest among migrants from "other districts." With the exception of the youngest age group, migrants from "other districts" have higher proportion of "ever users" and "current users" of family planning than nonmigrants or migrants from India throughout the age structure. The highest proportion for both "ever users" and "current users" was reached at ages 35-39 years. Indian migrants in contrast had the lowest proportions of "ever users" and "current users" throughout the age structure (with the exception of the age group 35-39).