This study examined the differences in age; sex; education; occupation; reasons for migration of rural-urban and urban-rural migrants; ecological characteristics, such as population size and density; unemployment rates; employment rates; and division of labor in Thailand from 1975-1980. It was hypothesized that high in-migration to rural regions is explained by low population size and low density, high employment, and high division of labor; that urban in-migration is accounted for by high population size and density, high employment rates, and high division of labor. The data were a 1% census sample tape from the 1980 Thai Population and Housing Census, which included sex, age, educational attainment, migrants' occupation, and reasons for moving into rural or urban areas. The analysis showed that people moved to urban areas because of job opportunities for both specialized and low-skilled workers. In contrast, people, particularly very young and retired males and females of almost all ages, moved to rural areas to accompany household members. Other family-related reasons for migration included change in marital status, to return home, to be ordained, or to seek higher education. Men with a wide variety of skilled occupations moved to cities, most often to look for work. Women moving to urban areas were engaged in service work. Highly educated males tended to move to rural areas for government work. People of both sexes relocated to rural areas to do agricultural work. It is recommended that family needs and patterns among migrants be considered by policymakers in Thailand in their effort to minimize socioeconomic inequalities between rural and urban areas. Specific recommendations included establishing agricultural service industries and growth centers in rural areas, decentralizing economic activities to the surrounding Bangkok provinces, creating educational opportunities in rural areas, providing more professional jobs for educated young migrants in urban areas and offering social welfare such as health insurance and child care for young female service workers in urban areas.