This research project was designed to demonstrate the usefulness of a supportive intervention program for 17 nine to 14 year old siblings of autistic children. Current clinical practice has begun most recently to include the siblings of handicapped children in treatment services as a preventive measure to help maximize families' coping abilities and to increase the chances that they will be strengthened by their unique circumstances. Although research evidence suggests that most siblings are not at risk for serious psychopathology, it seems reasonable to assume that few remain unaffected by living with a handicapped brother or sister. Siblings report that they have increased responsibilities, many unanswered questions, and parents who typically are caught up in the stresses of caring for a handicapped child and have limited time to attend to their needs. It was hypothesized that an intervention program providing information about the handicapping condition, autism, and offering support through participation in a discussion group with other siblings of autistic children would effect improved coping in the participants. Three time-limited interventions (information plus support, information plus activity, and activity control) were compared under controlled conditions. Sibling coping was measured by a) a battery of self-report and parent ratings of behavior and attitudes, b) clinical observations, and c) sibling and parent anecdotal accounts. Descriptive behavioral and attitudinal data on the total sibling sample indicated more deviant individual profiles than would be expected in the normal population. Consistent with previous research and clinical practice with this subject population, children who were identified with problems were those generally thought to be at greatest risk such as older female and younger male siblings who have assumed extensive caretaking responsibilities for the autistic child. Specific group changes following intervention were confounded by individual subject reactions to the various procedures. Qualitative aspects of the siblings' participation were discussed in terms of implications for future clinical intervention and research with this sibling population.