The purpose of the current study was to conduct a pilot investigation to determine the effectiveness of Multisystemic Therapy (MST) for improving regimen adherence and metabolic control among adolescents with poorly controlled Type 1 diabetes. Thirty-one adolescents were randomly assigned to either MST or a control condition. MST treatment lasted approximately six months. Data were collected at study entry and at a six-month posttest. Twenty-five adolescents completed the study. Adolescents who received MST had significantly improved adherence to blood glucose testing and metabolic control from study entry to the six-month posttest, whereas controls did not. Adolescents receiving MST also had a decreased number of inpatient admissions at the six-month posttest. Improvements in metabolic control were related to improvements in parent report of adolescent adherence. Results suggest that MST holds promise as an intervention for improving adherence behavior and health outcomes among adolescents in poor metabolic control.