In the present pilot study, an attempt was made to shape and maintain cigarette smoking behavior in rhesus monkeys both with and without the simultaneous use of other reinforcers. Initially, 14 monkeys were trained to suck air and puff on cigarettes using sweetened liquid reinforcer. After smoking had been established, the sweetened liquid reinforcement was removed. Smoking without this reinforcement, referred to as 'voluntary smoking,' was then observed during 20-h daily sessions. Of 14 monkeys studied, 2 have engaged in voluntary smoking for 2 years or longer. The maximum figures recorded for any single 20-h session were 3,271 puffs (20 cigarettes) in one monkey and 16,384 puffs (47 cigarettes) in the other. Although the baseline variability of smoking by these monkeys was quite high, low-nicotine and nicotine-free cigarettes seemed to lead to clear decreases in smoking. In 2 other monkeys that did not perform voluntary smoking, smoking was reestablished under a random-time or a tandem schedule for sweetened liquid reinforcement. Within this situation ('schedule-controlled smoking') schedule manipulations also led to changes in intake of cigarette smoke. The voluntary smoking model described in the present paper should be useful for studying the factors involved in initiating and maintaining smoking behavior and for studying the psychopharmacological effects of smoking, while the schedule-controlled smoking model should be useful for studying the physiological effects of smoking and for studying th relationship of smoking with various disease entities.