This article considers issues pertaining to the linkages between rural populations, migration from and to rural areas, and the environment - focusing on developing countries in the latter part of the 20th century. The article concentrates on internal migration, although it does briefly discuss the state of knowledge on the interplay between international migration and the environment. It addresses questions such as: What are the recent and projected patterns of rural population growth? How much internal migration in developing nations is towards rural environments? What kinds of rural environments are people moving into, in what countries, and what are the environmental consequences? Are there relationships in the other direction as well - that is, does environmental deterioration play an important role in out-migration from rural areas? And does out-migration from rural areas have environmental effects on the places of migratory origin? The article concludes with policy recommendations.