Little is known about the role of adolescent neurodevelopment in adolescent substance abuse treatment outcomes. The development and evaluation of adolescent substance abuse treatments rarely includes consideration of varying cognitive capacities and their neural representations as determinants of individual variation in treatment response. This proposed R21 project would address this gap by identifying associations among decision making, task-related neural processing, and treatment outcome among adolescents participating/have participated in two randomized clinical trials for adolescent substance abuse. Increasing our understanding of neural processes that underlie decision making in adolescent marijuana and alcohol users would inform the development of future intervention and prevention efforts.