Theories of primate social structure argue that patterns of food availability have a profound impact on social organization. For instance, if food resources are dispersed in small, scattered clumps, competition among group-living individuals will increase and limit the number of animals that can feed and move together; this will constrain group size. This study aims to gather data to test such ideas, particularly the proposition that food may be a limiting factor only at times of seasonal food shortages. The study species, the mona monkey, occurs in a range of forest habitats in West Africa, but has never been the subject of a long-term field study. Studies of related species suggest that much of its diet is ripe fruit and insects, food items likely to fluctuate greatly in their seasonal abundance. Research on the behavior of the mona monkey, and on the ecology of its habitat, will take place in the Lama Forest of Benin, which has a long dry season. Lama is the largest surviving remnant of the original dry forest vegetation of the Dahomey Gap, an area thought to have played a major role in the evolution of West African mammal species. This research will contribute to the better conservation of this threatened ecosystem.