This study examined the relationship of family functioning and depressive symptoms with self-management, glycemic control, and quality of life in a sample of adolescents with type 1 diabetes. It also explored whether self-management mediates family functioning, depressive symptoms, and diabetes-related outcomes. Structural equation modeling was used to estimate parameters in the conceptual causal pathway and test mediation effects. Adolescents (n = 320) were primarily female (55%), younger adolescents (58%), and self-identified as White (63%). Self-management mediated the relationship between family conflict, family warmth-caring, parent guidance-control, and youth depressive symptoms with glycosylated hemoglobin (A1C). In addition, self-management mediated the relationship between family conflict and youth depressive symptoms with quality of life. Supporting optimal family functioning and treating elevated depressive symptoms in adolescents with type 1 diabetes has the potential to improve self-management, glycemic control, and quality of life.