Reducing morbidity and mortality related to overweight and obesity is a public health priority. Various interventions in school and worksite settings aim to maintain or achieve healthy weight. To identify effective strategies for weight control that can be implemented in these settings, the Task Force on Community Preventive Services (Task Force) has conducted systematic reviews of the evidence on nutrition, physical activity, combinations of these interventions, and other behavioral interventions (e.g., cognitive techniques such as self-awareness and cue recognition). Task Force recommendations are based on evidence of effectiveness, which is defined in this report as achieving a mean weight loss of > or =4 pounds, measured > or =6 months after initiation of the intervention program. The Task Force recommends multicomponent interventions that include nutrition and physical activity (including strategies such as providing nutrition education or dietary prescription, physical activity prescription or group activity, and behavioral skills development and training) to control overweight and obesity among adults in worksite settings. The Task Force determined that insufficient evidence existed to determine the effectiveness of combination nutrition and physical activity interventions to prevent or reduce overweight and obesity in school settings because of the limited number of qualifying studies reporting noncomparable outcomes. This report describes the methods used in these systematic reviews; provides additional information regarding these recommendations; and cites sources for full reviews containing details regarding applicability, other benefits and harms, barriers to implementation, research gaps, and economic data (when available) regarding interventions.