We seek to devise and standardize procedures that can be effectively employed to study the effects of drugs on the behavior of stumptail macaques (Macaca arctoides) living in a social group. We will determine the effects of a variety of drugs on different types of behaviors and social interactions that typically occur in a heterogeneous group of monkeys free-ranging within a large open-air-enclosure, and we will examine how the effects of each drug depend on such factors as type of behavior, the dominance rankings of the subjects, the social context in which the behavior occurs, etc. Our main goal is to characterize the effects of selected drugs on readily identifiable behaviors exhibited by a social group of nonhuman primates. Experiments are concerned with the effect of acute administration of a range of doses of three behaviorally active drugs (d-amphetamine, pentobarbital and morphine). The experiments are designed to determine dose-effect relationships and the time course of drug effects. The dependent variables will be quantitative measures of different behavioral activities of individual subjects and the entire group.