A primary goal of this study is to establish an ethogram for the Mongolian gerbil (Meriones unguiculatus), i.e., to define, describe and categorize the behavioral units exhibited by gerbils living in a communal, laboratory habitat. To this end, a complex habitat (containing such physical and biotic elements as an artificial burrow system, digging substrate, conspecifics, rocks and tree branches) will be developed so that a wide range of the animal's behavioral repertoire will be expressed. A number of recording techniques (e.g., videotape film and time-sampling procedures) will be employed in the broad description and analysis of the social and non-social behaviors exhibited in this "gerbarium" so as to define classes of reliable, easily recognizable and constant behavioral units, and some of the environmental factors and situations which affect these species-typical response classes. With this broad behavioral profile, and its relationships to a number of independent variables (e.g., light-dark cycle, social context, and physical artifacts), attempts will be made to examine within this behavior-rich environment the stability and nature of behaviors altered or elicited by chemical brain stimulation, and thereby broaden the perspective on the relationship between central neurochemical events and behavior.