PROJECT SUMMARY/ABSTRACT Adolescents have higher rates of alcohol consumption than any other age group, and Alcohol Use Disorder (AUD) typically onsets during the adolescent years, prior to the legal drinking age. Accordingly, theoretical models of AUD suggest that early drinking experiences influence the progression of AUD symptoms. Further, repeated drinking is thought to alter the brain?s reward systems, leading to clinical manifestation of AUD over time. These theories are founded in direct research of alcohol?s effects with adolescent animals and laboratory or retrospective reports with human adults. However, concepts such as adolescents? subjective alcohol responses and craving are difficult to model in animals and may not be accurately reflected in human adults with several years of drinking experience. Thus, innovative research that taps these constructs in human adolescents is essential to build theory and inform practice. This resubmission of K23 proposal AA024808-01, Novel Approaches to Understanding How Alcohol Pathology Develops in Adolescents, outlines a well-integrated research and training plan for mentored, patient-oriented career development. The proposed research seeks to understand how subjective responses to alcohol and craving change during the developmentally-critical period of adolescence through the application of longitudinal ecological momentary assessment (EMA) paired with psychophysiological assessment in a more controlled setting. Participants, ages 15 to 17 years, who report alcohol consumption but do not meet criteria for AUD, will complete three, 24-day EMA bursts and three laboratory sessions over one year. Laboratory psychophysiological assessments will include mean arterial pressure, heart rate, and startle eye blink electromyography. EMA will include randomly sampled and self- initiated reports of subjective states across drinking and non-drinking days. Hypotheses of within-person processes of change will be evaluated primarily with longitudinal latent variable methods. This research plan provides the necessary landscape for experiential learning and mentored training in applying developmentally informed models of AUD to theory and practice, bridging laboratory and real-world research findings, and testing dynamic theories of AUD development. An impressive mentorship team with complimentary expertise in EMA methods, adolescent development, psychophysiological research, longitudinal modeling, and clinical research applications will guide training in these areas. The proposed 5-year career development period will facilitate a successful transition to independence and aid in securing future research funding to apply novel methods and statistics within a developmental framework. The proposed research seeks to address major barriers to the advancement of leading AUD theories, with the ultimate goal of identifying more effective prevention and early intervention approaches. Thus, this proposal is well-aligned with NIAAA?s underage drinking research initiative that promotes research to understand factors compelling youth to progress from initial alcohol use to harmful use to AUD.