PROJECT SUMMARY/ABSTRACT Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed developmental disorder of childhood, affecting ~9% of children nationwide. Although ADHD dramatically increases the risk for poor academic achievement, substance abuse and criminal behavior, particularly in adolescence, too little is known regarding how neurobiological developmental trajectories underlie these behavioral and clinical outcomes. This remains the case despite the importance of such work for earlier identification of risk factors, more targeted treatment models, and, in turn, education, juvenile justice, and healthcare savings for individuals, families, and society. The main goal of the parent grant, “Longitudinal investigation of the neurobiological underpinnings of risk behavior in ADHD throughout the adolescent transition: the key role of cognitive control and motivation network development” (R01MH119091), is to examine longitudinal neural, behavioral, and clinical trajectories of youth with ADHD from late childhood to mid-adolescence. We focus on neurobehavioral processes related to cognitive control, or executive function (EF), and motivation, as they have been identified as centrally important both to the etiology of ADHD and to the general increase in risk-taking behavior observed in typically developing (TD) adolescents. Notably, there is marked heterogeneity in terms of EF difficulties experienced by youth with ADHD. Youth with ADHD who experience EF difficulties are at higher risk of poorer outcomes than those without EF difficulties, regardless of severity of ADHD symptoms. Moreover, different components of EF differentially relate to outcomes. Specifically, youth with ADHD with deficits in updating have poor emotion regulation, while youth with ADHD with deficits in shifting have low academic achievement. Therefore, it is crucial to characterize longitudinal trajectories of distinct components of EF to identify youth with ADHD who are more at risk for future negative outcomes. Thus, in this supplement we propose to more thoroughly assess EF and to longitudinally characterize trajectories of functional brain network organization and multiple distinct EF components throughout the transition to adolescence in youth with ADHD and TD youth. We additionally propose to identify how these trajectories relate to adolescent outcomes. We achieve this by proposing an additional behavioral testing session for participants already enrolled in the parent study in which we administer a battery of EF tasks and assess academic achievement-related outcomes. By combining this new data collection with brain imaging, self-report, and parent-report data collected through the parent grant, we will achieve the following aims: 1) Characterize behavioral trajectories of distinct components of EF in ADHD throughout the transition to adolescence; 2) Characterize the relationship between trajectories of functional brain network organization and EF i...