PROJECT SUMMARY Alcohol use disorder (AUD) research typically analyzes relapse and recovery processes over short time-frames, such as during and immediately following a treatment episode. The long-term trajectories of recovery, the impact of relapse episodes, and their associated neurobehavioral markers and precipitants comprise a vital gap in our scientific understanding of the recovery process. Our goals are to provide a scientific understanding of recovery and relapse, as well as to identify novel targets for future relapse prevention interventions. Specifically, changes in the mechanisms underlying AUD will be investigated using the Competing Neurobehavioral Decision Systems (CNDS) framework, which posits that addiction and relapse arise from a regulatory imbalance between the impulsive and executive decision systems. To pursue this goal, participants with AUD will be recruited from the International Quit & Recovery Registry (IQRR), which was established in 2011 and currently has about 8,775 registrants. The IQRR provides a unique online resource that permits the scientific study of recovery processes and the highly efficient collection of data suitable for long-term repeated measurement research. We will use an accelerated longitudinal design, which allows the prospective characterization of psychosocial functioning, relapse, and CNDS functioning across 12 years of AUD recovery by recruiting participants with a range of different recovery lengths, up to 10 years. Over three years, participants will complete quarterly assessments, including measures of CNDS functioning. In Aim 1, we will examine the psychosocial functioning over long-term AUD recovery and how it is impacted by CNDS regulation. In Aim 2, we will examine relapse over long-term AUD recovery and how it is impacted by CNDS regulation. In Aim 3 we will examine the dynamic interaction of CNDS processes impacting the recovery using computational modeling. Together, the findings from this rigorous and innovative research project will improve our understanding of the temporal dynamics and underlying mechanisms of recovery from AUD.