The matching law suggests that behavior is emitted in proportion to the level of reinforcement available. The current study investigated this effect in individuals with autism spectrum disorders (ASD), and focused on the effects of magnitude of reinforcement (Study 1), and rate of reinforcement (Studies 2 and 3), on matching performance. Studies 1 and 2 employed lower functioning children with ASD, and demonstrated matching in both groups, but that the group with ASD displayed greater levels of stimulus bias. Study 3 employed higher functioning children with ASD, and found little evidence of matching, but higher stimulus bias in the group with ASD. These effects suggest a disruption of stimulus control, but not reward sensitivity, in individuals with ASD. (Contains 3 figures.)