The present research experimentally evaluated a “naturalistic” treatment program for an autistic child administered by the parents over a 2‐yr period. Operant reinforcement techniques previously developed and tested in laboratory settings were initially assessed in a clinic and eventually in the family's home. Experimental manipulations were performed in both settings on rituals, crying and whining, compliance, non‐verbal imitation, and verbal imitation. The results clearly indicated that parents can effectively treat autistic behaviors provided that they receive adequate training and supervision in operant reinforcement therapy, and provided that sufficiently potent reinforcers are available to maintain b