Nine male research volunteers, in three groups of three subjects each, resided in a residential laboratory for up to 25 days. All contact with the experimenter was through a networked computer system and subjects' behaviors including food intake were continuously recorded. Subjects brought their own activities such as model-making, and these in combination with those provided by the laboratory resulted in rich behavior repertoires. During the first part of the day, subjects remained in their private rooms doing planned work activities, and during the remainder of the day, they were allowed to socialize. Cigarettes containing active marijuana (1.84% THC) or placebo were smoked prior to the private work period and during the social access period. A single active marijuana cigarette prior to the private work period had no effect on food intake. The administration of two or three active marijuana cigarettes during the social access period increased average daily caloric intake. The increased intake was due to an augmentation of calories consumed as between-meal snack items rather than an increase in meal size per se.