To examine whether individual psychological variables mediate the family conflict-glycemic control relationship. During three study visits spanning 9 months, 147 adolescents with type 1 diabetes completed questionnaires measuring anxiety and depressive symptoms, and diabetes-specific worry. Caregivers similarly completed a measure of diabetes-specific family conflict. Blood glucose monitoring frequency and glycemic control were also obtained during study visits. Separate mediation analyses revealed that anxiety was the only individual psychological variable that mediated the caregiver-reported family conflict-glycemic control link. Anxiety accounted for 20% of the family conflict-glycemic control link, compared to 8.5% for depression and 6% for diabetes-specific worry. Results suggest that anxiety symptoms may be promoted in a family environment characterized by conflict and these symptoms have detrimental effects on glycemic control. Continued monitoring of family functioning and adolescents' anxiety symptoms, as well as refinement of interventions, is needed to promote positive health outcomes.