Two experiments were conducted with 4 students with autism to test the relationship between either toys or books as conditioned reinforcers for observing or playing and their effect on stereotypy and passivity. Experiment 1 consisted of a single preschool student who emitted frequent intervals of passive behavior and infrequent intervals of looking at books in a free play setting. After systematic training sessions involving pairings of reinforcers with looking at books, he engaged in looking at books significantly more than in his baseline in free play and decreased intervals of passivity. Experiment 2 involved a multiple baseline across 3 students. Baseline data were followed by toy-play conditioning sessions run concurrently with free-play observations. The 2 students who emitted frequent rates of stereotypy in baseline had significantly fewer intervals of stereotypy after toys were conditioned as reinforcers and toy play increased for all 3 students.Stereotypy is a prevalent behavior of children with autism.