The worksite is a particularly promising setting for implementing multi-level interventions to prevent weight gain. However, in order to take full advantage of the very large reach of worksites, the intervention must have several important characteristics. It must be practical, affordable, and adaptable to a wide variety of worksite types and diverse work forces. In addition, in order to be sustained, it must be championed by a lead agency that has health promotion through worksites as an important part of its mission. The current proposal describes such a program. The current proposal is a joint effort of the Brown University Medical School (including the Institute for Community Health Promotion), Blue Cross/Blue Shield of Rhode Island, the Worksite Wellness Council of Rhode Island and the RI Department of Health. Each partner has major roles and responsibilities and brings their unique perspectives and considerable resources to a joint project to test a multi-level program on worksites to assist workers to increase their weight management skills and behaviors. The proposed project is designed to test two separate but interrelated Specific Aims: S.A.1 To test the effectiveness of a multilevel worksite wellness program to impact employee weight, dietary intake and physical activity, compared to an attention placebo condition. S.A.2. To begin national dissemination to other large third party payers and target coalitions of worksites through packaging of programs, materials and protocols; analysis and presentation of program results and costs. Accomplishment of S.A.1, will be determined by a two group randomized effectiveness study (Treatment vs. Comparison) utilizing 24 RI worksites with randomization by site. The specific impact and outcome evaluation measures (BMI, DHQ-FFQ, and 7-day PAR) will be collected at Baseline, 12, 24 and 36 months on a longitudinal cohort selected at random from the employee lists of each participating worksite. An additional random cross-sectional sample drawn at 36 months will allow for pre-posttest cross-sectional analyses as well. Extensive process evaluation and a mediating variable framework are also included to identify the mechanisms in successful change at both the worksite and individual level, which will maximize the potential for national dissemination of the intervention as well as advance theory and improve intervention practice and policy.