Project Abstract/Summary Prevention of youth-onset type 2 diabetes (T2D) is critical. Rates are escalating, especially in adolescent girls of color, and youth-onset T2D is difficult to treat and presents with a more aggressive course than adult-onset. Efficacious T2D prevention requires a more rigorous understanding of the underlying mechanisms of action that facilitate behavior change. Although physical activity is protective against worsening insulin resistance, a key antecedent of T2D, exercise training shows insufficient effectiveness for producing sustained change in physical activity, weight, or metabolic health in adolescents with obesity. The overarching hypothesis of the parent study, R01DK111604-01, is that depression is a driver of the difficulties that many adolescent girls at risk for T2D experience in initiating/sustaining physical activity. In the parent RCT, we are testing the hypothesis that delivering an empirically-supported depression intervention, cognitive-behavioral therapy (CBT), to decrease depression, followed sequentially by exercise training, will offer an efficacious strategy for increasing physical activity and improving insulin resistance. In this administrative supplement (NOT-OD-22-140), our overarching goal is to illuminate executive functioning (EF) dimensions that underlie decreasing depression and increasing physical activity. EF is theoretically central to self-regulation of cognitions/behaviors that support physical activity initiation and maintenance. Yet, in adolescents with obesity, most data are associational, directionality is unclear, and specific EF dimensions relevant to physical activity are not entirely understood. Elucidating dynamic, time- ordered changes that unfold in depression, EF, and physical activity throughout 12-week CBT/exercise could facilitate future intervention tailoring/optimization for adolescents at risk for T2D with mood concerns. However, rigorous tests of mechanisms of action require intensive repeated measures to capture temporal ordering during the intervention phase, making it essential to first establish feasibility/acceptability of intervention-phase intensive, repeated measures. Leveraging the parent RCT, we propose a feasibility and proof-of-concept study of EF as mechanism of action in N=95 (sample subset) adolescent girls at risk for T2D with elevated depression. Specific aims of this 1-year supplement are to: (1) Test feasibility/acceptability of intensive repeated measures of depression, EF, and physical activity across four 12-week (6-week6-week) sequences in girls at risk for T2D: i) CBTexercise, ii) exerciseCBT, iii) CBTCBT, and iv) exerciseexercise; (2) Describe longitudinal/ time-ordered changes and change-to-change associations for depression, EF, and physical activity across the intervention; and (3) Explore group differences in longitudinal/time-ordered change-to-change associations. This supplement fosters new collaborations with experts in neurocognit...