The purpose of this study is to test the effectiveness of a practical, low-cost, low-intensity behavioral intervention that can be integrated directly into diabetes clinic routines. The goal of the intervention is to prevent the deterioration in glycemic control, treatment adherence, and quality of life that often occur during the transition to adolescence in families of youth with type 1 diabetes. Four-hundred and eighty families (120 from each of the four sites) will be randomly assigned by the coordinating center to intervention or standard care conditions. Standard care will be the multidisciplinary management of type 1 diabetes as currently practiced at the clinical sites. Randomization will be stratified by main versus recent-onset subgroup, age, and for the main subgroup, baseline glycosylated hemoglobin level. Families will remain in their respective experimental conditions for 24 months. A trained health advisor will be responsible for interactions with parents and patients prior to each diabetes clinic visit (preparation phase), at the time of the diabetes clinic visit (consolidation phase) and by phone, e-mail, etc. after the clinic visit (follow-up phase). Using educational modules developed for the study, families will be engaged in problem identification and solving activities to foster improved disease management capabilities and improved parent-youth communication around and sharing of responsibility for diabetes management. Families will be assessed at home three times and in the clinic four times over the course of the study. Measures include parent, child, and family characteristics that may affect intervention effectiveness, targeted mediators, family interaction, management practices, and glycosylated hemoglobin (HbA1c). Primary outcomes are diabetes management adherence and metabolic control; secondary outcomes are quality of life, health status, and psychosocial status.