Treatment options for maladaptive repetitive behaviors associated with autism are limited. This is particularly so for ritual and compulsive forms of repetitive behavior, which commonly interfere with adaptive activities and may cause distress to individuals with autism and their families. The present study assessed an avoidance extinction approach to treatment of frequent, idiosyncratic ritual and compulsive behaviors among a small clinical sample (n = 3) of adults with autism and intellectual disability. Single case experimental design results indicate that intervention achieved extinction for 2 of the 3 participants, with the third showing a marked decrease in target behavior. A distinct extinction pattern consistent with functionally avoidant behavior was noted for the two participants who best responded to treatment.