The overall objective of the proposed research is to demonstrate the usefulness of state of the art statistical methods for answering alcohol research questions of key importance to prevention. To achieve this objective the proposed research will undertake a secondary analysis of the National Longitudinal Survey of Youth (NLSY), a nationally representative sample of 12,686 young adults. Data from the NLSY provide extensive longitudinal information on the development of alcohol abuse and dependence. In relation to other alcohol data sources, the NLSY is unique in its combination of a large sample size, many time points of observation, multiple cohorts, and several indicators of alcohol use disorders. The longitudinal nature of the data provides significant opportunities for studying the etiology of alcohol use disorders and the critical factors for identifying individuals at risk, issues which are important to prevention research. The proposed research will highlight new statistical methods for categorical and other non-normal data using latent variable constructs and repeated measures. The secondary analyses will have two aims: (1) to assess and describe patterns of stability and change in the prevalence of DSM-IV alcohol abuse and dependence over time, and (2) to analyze the trajectories of alcohol use across young adulthood and relate them to risk factors associated with alcohol use disorders.