Alcohol use and disorders are rapidly increasing in the United States, especially among women. Available evidence suggests that recent these increases in drinking among women are historically unprecedented, and outpacing men, indicative of converging gender differences. The reasons why, and what to do about it, is forming a critical gap. Indeed, intervention and prevention efforts require urgent information about when historically these convergences have occurred, whether convergence is limited to certain age groups, and most critically, why. Further, increases in drinking among women portend a potential public health crisis, requiring diligent forecasting of future burden. Without such information, intervention and prevention efforts can be misplaced, focusing on the wrong age groups, or the wrong mediating factors. Only data with sufficient variation both historically and developmentally can answer foundational questions about converging gender differences in alcohol-related outcomes and the future burden that can be expected if action is not taken. Drawing from a lifecourse perspective, the present project will utilize 47 longitudinal cohorts collected through the Monitoring the Future (MTF) project, from 1976 through 2022, and apply rigorous age-period-cohort growth curve modeling to provide a better understanding of: when in historical time and during what developmental periods from age 18 to 45 gender differences have been converging; how gender differences are converging (i.e. because women are increasing drinking, men are decreasing, or both), and why gender differences are converging, examining an unprecedented array of potential mediating factors including sociological trends in role tradition (marriage, parenthood, education, residential status, and employment), gender and societal attitudes, and psychological (drinking attitudes and reasons, future intentions for partnership and parenthood, parenting and marriage satisfaction) as potential mediators. We will employ rigorous age-period-cohort growth models to accomplish three aims with respect to three outcomes (30-day drinking, binge drinking, and alcohol use disorder symptoms): (1) Test when in historical time and at what developmental age gender differences in alcohol consumption, binge drinking, and alcohol use disorder symptoms are converging or have converged for men and women; (2) Forecast future public health burden of alcohol consumption, binge drinking, and alcohol use disorder symptoms and (3) Analyze sociological, psychological, and attitudinal factors as potential mediators of gender convergences across historical time and developmental age. Mediation will be estimated with novel methods developed for epidemiological applications that overcome problematic assumptions of previous approaches. MTF data have been the seminal source of information on substance use during the transition to adulthood for more than four decades, but with few exceptions have not been used to examine age-period-cohort trends in gender differences in alcohol consumption. Alcohol use among women across both the lifecourse and generations remains poorly understood and represents an important gap in the literature; our proposed use of MTF data stands to be a seminal contribution.