High levels of alcohol consumption clearly place individuals at great risk and present a significant health and economic burden to society. Emerging evidence indicates that many young adults engage in what can be called extreme drinking (i.e., drinking at levels likely to lead to BACs > .16). Despite recent attention to extreme drinking5,6, we know surprisingly little about this behavior beyond associations revealed by cross‐sectional studies that rely exclusively on retrospective self‐report. The proposed study is designed to provide some of the first comprehensive data about influences on the extreme drinking phenotype, and to compare these with those identified for the typical binge drinking phenotype. Whether there are unique causes and correlates of extreme drinking (compared to binge drinking) is an empirical question that has not been tested. There are challenges to investigating extreme drinking, including 1) overcoming the limitations of retrospective self‐report, 2) adequately measuring personological and environmental influences, and 3) capturing the temporal associations of these diverse influences and their impact on extreme drinking occasions. The proposed project is designed to meet these challenges using a combination of laboratory, genetic, and ecological momentary assessment (EMA) methods. Our multi‐method approach will combine laboratory alcohol administration, EMA, and real‐time BAC assessment to capture the interplay between a broad range of potential influences on extreme drinking, extend our investigation outside the lab and into the natural drinking environment, and explore the temporal associations of influences on extreme drinking. We focus on four core constructs central to current theoretical models of addiction that are hypothesized to influence substance use through in‐the‐moment processes: reward sensitivity (RS), incentive salience (IS), impulsivity/loss of control (Imp), and negative affectivity (NA). We will recruit a sample of 400 young adults (ages 21‐29), ascertained from a statewide DMV database, who have a recent legal action with a recorded BAC consistent with extreme drinking (≥ .12). Using a longitudinal burst design, we will follow participants over a 12‐month period, with five self‐report assessments and four, two‐week EMA bursts. A baseline laboratory session will assess behavioral, trait, and electrophysiological markers of core study constructs. We aim to (1) Evaluate the validity and utility of real‐time assessments for identifying extreme drinking and alcohol‐related behavior. This aim could inform estimation methods for characterizing extreme drinking and guide refinement of definitions of problematic drinking profiles. (2) Characterize the structural influence of stable individual differences, transient intra‐individual factors, and environmental variables on risky, binge, and extreme drinking occasions and alcohol‐related negative consequences. This aim will reveal the incremental validity of st...