ABSTRACT The Prevention Research Center (PRC), a division of Pacific Institute for Research and Evaluation (PIRE), was founded in October 1983 around the `Environmental Approaches to Prevention' Research Center grant, se- lected following peer review as the National Institute on Alcohol Abuse and Alcoholism (NIAAA) national Cen- ter for prevention research. The overall goals of the Center are to: (1) undertake innovative basic research that informs the development and implementation of cost-effective environmental prevention policies and programs at the organizational, local, state, and national levels; (2) undertake translational research of applied and prac- tical importance, including implementation, efficacy, and effectiveness studies focused on interventions to pre- vent alcohol-related problems, especially those addressing environmental factors; (3) summarize and synthe- size new and existing knowledge about prevention theories, policies, and programs, and to disseminate this information to professional, academic, and community audiences; and (4) provide multidisciplinary training and research opportunities for post-doctoral fellows and other early investigators. A key focus of the proposed Center Grant renewal is to investigate the potential of local alcohol control policies and other prevention efforts to reduce neighborhood and community alcohol problems by changing the oppor- tunity structures for drinking in ways that can effectively ameliorate harms. With an eye towards developing novel context-related real-time interventions, we will investigate the social and situational conditions that affect adolescents' and young adults' decisions regarding transitions in nighttime drinking contexts before and after the legal drinking age, and corresponding changes in risks for heavy alcohol use and related consequences (Component #3). We will investigate the combined influences over time of local alcohol and marijuana regula- tory policies, enforcement activities, and retail alcohol and marijuana availability on alcohol and marijuana use, co-use, and related problems during adolescence and early adulthood (Component #4). We will examine eth- nic differences in alcohol and marijuana co-use and related problems in a prospective cohort study of young adults, and the extent to which local alcohol and marijuana policies, enforcement, and illegal and legal mariju- ana availability affect ethnic disparities over time (Component #5). We will examine alcohol use and related harms during life transitions among older adults to help inform alcohol policies and other interventions relevant to this growing, but understudied, population (Component #6). We will investigate mechanisms of policy effects at the local level and address a critical gap in research on the physical availability of alcohol and alcohol-re- lated problems by examining the role of alcohol sales from on- and off-premises outlets with 30 years of data from the Western Australia Alcohol Indic...