This research examines the effects of task interspersal and density of reinforcement on several behaviors of an autistic 6-year-old boy during the performance of a visual matching task and two auditory matching tasks. Experiment 1 investigated the effects of interspersing high and low accuracy tasks on correct matching responses, positions of matching responses, looking away, and self-injurious behavior (SIB). The effects of interspersed trials were evaluated using an ABAB multiple treatments design. Results indicated that interspersed trials produced slightly more correct responses during the visual matching task; however, correct responses decreased during the other two tasks. The use of interspersed trials also decreased looking away from the stimuli and SIB. Experiment 2 evaluated the effects of reinforcement density apart from task interspersal. Two conditions, reinforce-corrects-only and reinforce-all-responses, were compared in Experiment 2. Correct responses increased slightly for all three tasks during the reinforce-all-responses condition. Looking away and SIB were very infrequent throughout Experiment 2.