High-intensity drinking (consuming 10+ drinks in a row) among young adults has recently been acknowledged as a serious health problem that requires urgent research attention. During the initial grant period (R01AA023504) we documented prevalence, predictors, and developmental change in retrospective recall of any past 2-week high-intensity drinking from ages 18 to 30 through secondary data analysis of the national Monitoring the Future (MTF) study. The current application is to collect new intensive longitudinal data to examine occasion-specific predictors and consequences of binge and high-intensity drinking at the period of the lifespan (ages 19-22) where alcohol use is the greatest. Information on occasion-specific predictors and short- and long-term consequences of binge and high-intensity drinking is needed to identify the motives, contexts, and public health impacts that differentiate these heavy levels of alcohol consumption. Building on our recent findings that used biennial data from the nationally representative Monitoring the Future (MTF) study, the current application is to conduct new primary longitudinal data collection from a national sample of high school students followed into young adulthood. Participants (modal age 18; N=2000) from the 2018 MTF 12th-grade baseline surveys will be selected (with an oversample of high school binge drinkers) for a 4-year web-based measurement burst study across the transition into young adulthood. Up to 56 days of data collection per respondent will be obtained using 4 annual data collection bursts (14 consecutive days of daily surveys per year at modal ages 19, 20, 21, and 22). Specific aims are to examine: (1) when and for whom high-intensity drinking is most likely to occur by focusing on occasion-level predictors (e.g., affect, motives for drinking, drinking contexts, and other substance use) and time-varying developmental predictors (e.g., college attendance, employment, living with parents) of gender-specific rates of high-intensity drinking (8+/10+ drinks for women/men), compared to binge (4-7 for women, 5-9 for men) or moderate (1-3 for women, 1-4 for men) drinking occasions; (2) whether acute consequences (e.g., blackouts, injury, aggressive behavior, sexual risk, and negative interpersonal consequences) associated with high-intensity (compared to moderate and binge) drinking differ across days and based on developmental and sociodemographic characteristics; and (3) longer- term patterns of alcohol-related consequences (ages 18-22) and whether they differ by gender and social roles including educational experiences (e.g., 2-year and 4-year college). The project will be the first national study of both college attenders and non-attenders to identify occasion-level predictors and occasion-level consequences of specific occasions of binge and high-intensity drinking. This will provide critical information for health promotion and intervention efforts targeting high-risk alcohol behaviors among young adults.