The study, involving 15 autistic children (2-7 years old) and their families investigated the short term effects of a treatment model in which parents are trained as co-therapists in teaching developmental skills and behavior management. Literature was reviewed on models for treatment of autism, studies of treatment efficacy with autism, and methodological issues for autism outcome studies (including the nature of treatment, subject selection and description, measures of therapeutic change, and overall design). The study tested four hypothesized effects of treatment: 1) parents would show an increase in the degree to which they are actively involved with their child during time spent together; 2) the autistic children would show an increase in the amount of time they either engaged in appropriate play or work, or interact with other people; 3) the autistic children would show a decrease in the amount of time engaged in inappropriate play with objects, in self stimulatory behavior, and in the time spent not interacting with either objects or people; and 4) the family would show an increase in their ability to handle the child's problems in the home without sacrificing other important aspects of family life. Direct behavioral observations and clinicians' ratings of family stress and adaptation (based on semi-structured interviews with mothers) were obtained during home visits at three times for each family. The overall results for the four main hypotheses indicated that the use of parents as co-therapists in the psychoeducational treatment of their own autistic children was effective. Parents became more actively involved with their children as a result of treatment. The autistic children showed more appropriate behavior as a result of treatment. Both inappropriate behavior by the child and the family's ability to cope with the autistic child improved over the treatment period, and showed trends toward significant treatment effects. Among appendixes are guidelines for behavioral observations, interview procedures, sample questionnaires on the effects of treatment, an apparatus checklist for home visits, a questionnaire on the effects of child problems on the family, guidelines for the initial research phone contact, and tables with statistical data. (SW)