Household and childcare responsibilities, peer contacts, and out-of-home activities of older same-sex siblings of mentally retarded children as compared to a group of matched nonhandicapped children were examined. Older siblings of retarded children, particularly older sisters, assumed multiple caretaking responsibilities. For these siblings, increased childcare responsibilities were associated with sibling conflict and decreased opportunities for peer contacts and out-of-home activities. As a group, however, siblings of retarded children did not differ from their agemates in frequency of contact with friends or participation in out-of-home activities. Retarded younger siblings had less contact with friends than did their nonhandicapped agemates. Within-group differences appeared to be more important in understanding sibling risk status than whether the child had a younger retarded sibling.