The immediate goal of this application is to provide the applicant trainee (Amy Levine, M.D.) with training in nutritional epidemiology and behavioral science. This training will lead to her obtaining a PhD degree in the Department of Epidemiology at the School of Public Health of the University of North Carolina at Chapel Hill. The applicant's long-term objective is to pursue a research career in the study of obesity, a major public health problem. Training in epidemiology will provide a rigorous methodologic base for the performance of quality research in populations. Training in behavioral science will provide a framework for studying behavioral causes and consequences of obesity. It will also allow the trainee eventually to develop and evaluate sound, theoretically-based community intervention strategies. The University of North Carolina at Chapel Hill will provide an rich environment for supporting research career development in nutritional epidemiology and behavioral science. The School of Public Health has strong departments of Epidemiology, Health Behavior and Health Education, and Nutrition, with a tradition of multidisciplinary research and collaboration. The departments of Epidemiology and Nutrition are jointly recruiting a senior faculty member in nutritional epidemiology to strengthen their research capability in this field. They are also co-developing an academic track in nutritional epidemiology for trainees. Also on campus is the NIH-funded Center for Gastrointestinal Biology and Disease. Center membership is made up of researchers from a variety of disciplines. Nutritional epidemiology represents one of the major research areas of the Center. The research proposed is a longitudinal study of weight loss behaviors in adolescents. A cohort of 9-llth graders will be followed for two school years. The aim of the study is (1) to follow the natural progression of weight loss behaviors over time and (2) to identify factors associated with weight loss behaviors. These factors will include sociodemographic variables, including race, sex, socioeconomic status, and weight status, and also attitudes, norms, and perceived control over weight loss behaviors, according to Ajzen's Theory of Planned Behavior. This theory has been shown to have predictive and explanatory power in describing a number of volitional behaviors, including weight loss. Subjects will be administered a questionnaire at baseline, then periodically throughout the study to measure sociodemographic characteristics, elements of the Theory of Planned Behavior, and weight loss behaviors. Weights, heights, and triceps skinfold measures will also be obtained, both to identify obese subjects and to assess the relationships of weight loss behaviors with actual weight change.