Four experiments are presented. The first experiment demonstrated that the incidence of stereotyped behavior was a monotonic increasing function of amphetamine dose. Variations in the form of the response to dose are described. The next two studies examined the relationship between environmental novelty and amphetamine-produced stereotypy. This behavior was observed less among subjects placed into novel environments than among subjects placed into familiar environments. The ability of novel stimuli to evoke exploratory responses incompatible with stereotypy was suggested as the basis for this effect. This interpretation was supported in a final experiment, which observed exploratory behavior and general activity, as well as amphetamine-produced stereotypy in subjects exposed to a novel stimulus in an otherwise familiar environment. All four experiments were interpreted as supporting a unified conception of amphetamine-produced and pathological stereotyped behaviors.