ABSTRACT There is a normative decrease in problem alcohol use that naturally occurs in the mid-20s after binge and heavy drinking peak, a process called “maturing out”. While most young adults mature out of problem use, a subset persist or escalate in their drinking; these individuals are at risk for lifetime struggles with alcohol use disorders. What differentiates those who mature out of problem drinking versus those who do not is not fully understood. Developmental changes in the brain are hypothesized to play a central role in the alcohol consumption shifts that define the maturing out period, as neural maturation is not fully complete until the mid- 20s. Furthermore, young adulthood is a critical neurodevelopmental period when subcortical emotion and reward-related and cortical cognitive control regions mature, concomitant with improvements in executive control and declines in impulsivity and sensation-seeking. Despite the presumed effect that neural maturation has on decreases in risky behavior (like heavy alcohol use), no study has directly tested associations between neurobiological processes and trajectories of alcohol use in young adulthood. For this study, we will recruit 400 individuals between the ages of 21 and 25 (50% female) who report at least one binge drinking episode a month for the past 3 months to undergo high-resolution structural magnetic resonance and functional imaging scans (cognitive control, emotion regulation, alcohol cue reactivity, and resting state) at baseline. Detailed neuropsychological and psychosocial measurements will also be collected. Follow-up assessments will consist of 1) self-report alcohol use, measured online every 3 months post-scan to examine trajectories of use, and 2) neuropsychological and psychosocial measurements, collected online every year post-scan. Participants will be recruited during Years 1–3. Follow-up assessments will be collected until the end of the study, maximizing the data collection period and allowing for a large follow-up age range (25–29 years). We will model alcohol use trajectories across time, using baseline imaging data as a marker to differentiate or predict participants who persist or desist in use. This design will allow us to 1) determine the extent to which neural and behavioral mechanisms of cognitive control, emotion regulation, and reward/cue reactivity predict drinking trajectories, and 2) examine the effect of problem drinking on these processes. As sex differences in cognitive control, emotion, and reward development likely introduce variability in alcohol use, 3) we will also characterize sex differences predictive of alcohol use trajectories. As an exploratory analysis, we will investigate neurobiological predictors of maturing out using multimodal (structure, resting state, task) MRI data analysis.