To test these views, we asked adolescents with diabetes and their parents to participate in a randomized study, to assess the impact of both multifamily group meetings and parent simulation of diabetes on youngsters' metabolic control as well as their psychosocial and family functioning. We hypothesized that the multifamily group interventions would produce significant improvements in youngsters' metablic status (Hb Al) relative to control adolescents, and that the groups with the additional parent simulation of diabetes would improve more than those receiving family intervention alone. We additionally hypothesized that, relative to controls, positive changes in youngsters' self-perceptions and parents' estimates of their youngsters' selfcare would result from the interventions. Although no specific hypotheses were advanced concerning changes in general family functioning and attitudes toward diabetes as a result of the interventions, we monitored adolescents' and parents' perceptions in these areas as well.