Project Summary Rapid escalations in substance use during adolescence confer risk for the development of substance and alcohol use disorders across the lifespan. Thus, identifying malleable risk factors and prevention targets that emerge before substance use onset is an important public health goal. Research demonstrates that delay discounting (DD), the tendency to perceive diminishing value in a reward as a function of the length of delay in its receipt, is an important and modifiable risk factor for substance misuse. However, the early developmental precursors of DD, including environmental adversity and genetic risk factors that are thought to be associated with increases in DD across adolescence are not well understood. The extant literature examining these vulnerabilities is limited by its reliance on poorly characterized markers of environmental adversity, lack of consideration of developmental effects, and the genetic contributions to the development of DD. The current application proposes to address these limitations utilizing data from the Adolescent Brian Cognitive Development (ABCD) Study, a national sample of youth (n = 11,875) with planned longitudinal assessments from age 9 to 17, spanning critical developmental periods for changes in DD and substance use. The proposed project will leverage rich and varied indicators of adverse childhood events and community environments (using the “Pair of ACEs” framework) and genetic data to create polygenic risk scores for DD (informed by findings from the largest available genome-wide association study of DD performed by project consultants). The project timeline will take advantage of both currently available and planned releases of data to test study aims and accelerate dissemination of findings from this landmark study. Specific aims of the study include: (Aim 1) to examine the structure of ACEs and its relation to early levels of DD; (Aim 2) to characterize the impact of ACEs on measured trajectories of DD over time; and (Aim 3) to investigate the joint associations between genetic and ACEs risk factors on changes in DD across adolescence. We also propose to explore whether developmental trajectories of DD mediate the relation between genetic and ACEs factors and subsequent changes in substance use frequency and severity. The research team brings together expertise in child development, delay discounting, genetics, and environmental indicators of risk, allowing for the most comprehensive study of the independent and joint contextual and genetic contributions to DD development. Findings from this project will provide mechanistic insights into the development of DD, in addition to specific and actionable advancements at the environmental level that may inform targeting of prevention approaches for reducing substance use among at-risk youth.