Overweight and obesity increase the risk of diabetes, heart disease, and cancer. Nearly two thirds of the US population is overweight or obese, accounting for 9-10% of health care expenditures. Worksite obesity interventions to date have not typically been characterized by strong methodological designs or assessed the long-term impact of intervention strategies - neither in terms of the benefits to the participants, i.e., meeting weight and health goals, nor in terms of benefits to employers, including increased productivity and decreased health care costs. The NIOSH WorkLife Initiative encourages further research in this area. The primary objective of this proposal is to compare the effectiveness of two individually tailored, integrated worksite weight management programs - Steps to Health (STH: usual standard of care) and Steps to Health Plus! (STH+) using a randomized controlled trial design (n=500) and follow-up at 12, 24, and 36 months. The primary endpoint will be weight loss at 36 months, with additional analysis to determine role of social-cognitive and behavioral (diet and physical activity) factors in intervention success. Further analysis will compare reductions in workplace injuries, health care utilization and claims costs, and absenteeism/presenteeism in the two trial arms during the two years following the intervention. For these outcomes, participants will also be compared, in a prospective (non-randomized) fashion, with individuals in an observational comparison group, who meet eligibility criteria but do not take part in either of the two interventions. Finally, we will estimate the costs of the interventions relative to their effectiveness and savings, including changes in absenteeism and presenteeism, workers' compensation claims, and health claim reimbursements. The proposal takes advantage of an existing comprehensive occupational surveillance system which will permit evaluating the impact of the intervention on health care reimbursements. The study will build upon and enhance a well-established institutional employee wellness program, most of the intervention costs will be provided in kind by the institution, and the multidisciplinary research team has broad experience with behavioral interventions, obesity and the workplace, and cost effectiveness analysis. The interventions will be evaluated in a health-care worksite with a population of mixed ethnicity and socioeconomic status, allowing greater generalizability. The results of this study should be of great value to worksites considering interventions encouraging healthy weight. The intervention site is especially pertinent in that health care institutions can be models for other workplaces, and health care workers can be models for their families and patients. The workplace may be an ideal setting for reaching large populations of overweight and obese adults with weight control programs; several federal agencies have called for further pursuit of this opportunity to improve public health. Steps To Health aims to 1) help workers meet and maintain healthy weight goals through healthy eating and increased physical activity, 2) reduce the rate of work-related injuries, and 3) decrease health care expenditures associated with obesity.