Based on field studies spanning nearly 40 years, this reference book summarizes and integrates past research with new and previously unpublished information on the behavioral ecology of Africa's red colobus monkeys from study sites as diverse as Senegal, Uganda and Zanzibar. It provides an unparalleled compilation of information on taxonomy, genetics, vocalizations, demography, social organization, dispersal, social behavior, reproduction, mortality factors, diet, ranging patterns, interspecific relations, and conservation. Social relationships in red colobus are less rigidly structured than in other African monkeys, resulting in considerable variation in social organization and group composition, both within and between taxa. This provides a unique opportunity to examine the extent to which social variables correlate with differences in habitat quality, demography, and predation by chimpanzees and humans. Unfortunately, at least half of the 18 taxa of red colobus are now threatened with extinction. Conservation problems are described, causal factors identified, and solutions proposed. This volume is intended not only to serve as a reference book, but to stimulate and guide future long-term research and to encourage effective conservation action.