Emerging adulthood is a transitional period for type 1 diabetes management, and aspects of family functioning such as family conflict and responsibility for diabetes management likely change following high school graduation. This study examined changes in diabetes-specific family conflict, family responsibility for diabetes management tasks, and associations with glycemic control up to 1 year after high school. Seventy-nine emerging adults with type 1 diabetes (M age = 18.09 ± .43 years; 51% female; 71% Caucasian) and their parents (73% female) completed self-report measures on diabetes-specific family conflict and family responsibility at 3 consecutive clinic visits, beginning in the spring of their senior year of high school. Hemoglobin A1c (HbA1c) was obtained from medical records. Diabetes-specific family conflict was relatively low; scores did not significantly change from baseline to Time 3. Parent responsibility for diabetes care decreased from baseline to Time 3. Higher parent- and emerging adult-reported family conflict and higher parent responsibility for diabetes care were associated with worse glycemic control (ps < .05). Parent-reported family conflict and the interaction between parent-reported family conflict and responsibility predicted HbA1c 1 year after high school. Conversely, HbA1c did not predict diabetes-specific family conflict or responsibility 1 year after high school. Findings indicate that diabetes-specific family conflict is associated with glycemic control after high school, even when emerging adults assume greater responsibility for diabetes self-care. Diabetes-specific family conflict levels were generally low and did not change over time despite this transitional period. If diabetes-specific conflict is present, it should be an important avenue for potential intervention for emerging adults with type 1 diabetes. (PsycINFO Database Record (c) 2019 APA, all rights reserved).