OBJECTIVE: To develop and test a family-centered behavioral weight loss intervention for African American adults with type 2 diabetes. METHODS: In this randomized trial, dyads consisting of an African American adult with overweight or obesity and type 2 diabetes (index participant) paired with a family partner with overweight or obesity but not diagnosed with diabetes were assigned in a 2:1 ratio to a 20-week special intervention (SI) or delayed intervention (DI) control group. The primary outcome was weight loss among index participants at the 20-week follow-up. RESULTS: One hundred eight participants (54 dyads-36 (SI) and 18 (DI) dyads) were enrolled: 81% females; mean age, 51 years; mean weight,103 kg; and mean BMI, 37 kg/m2 . At post-intervention, 96 participants (89%) returned for follow-up measures. Among index participants, mean difference in weight loss between groups was -5.0 kg, P <0.0001 (-3.6 kg loss among SI; 1.4 kg gain in DI). SI index participants showed significantly greater improvements in hemoglobin A1c, depressive symptoms, family interactions, and dietary, physical activity, and diabetes self-care behaviors. SI family partners also had significant weight loss (-3.9 kg (SI) vs. -1.0 kg (DI), P = 0.02). CONCLUSIONS: A family-centered, behavioral weight loss intervention led to clinically significant short-term weight loss among family dyads.