Objective: Evaluate a selective prevention program targeting both eating disorder symptoms and unhealthy weight gain in young women. Method: Female college students at high-risk for these outcomes by virtue of body image concerns (N = 398; M age = 18.4 years, SD = 0.6) were randomized to the Healthy Weight group-based 4-hr prevention program, which promotes gradual lasting healthy improvements to dietary intake and physical activity, or an educational brochure control condition. Results: Compared to controls, intervention participants showed significantly greater reductions in body dissatisfaction and eating disorder symptoms, and greater increases in physical activity, at posttest and significantly greater reductions in body mass index (BMI) and self-reported dieting at 6-month follow-up. Moderator analyses revealed significantly greater reductions in eating disorder symptoms for those with initially elevated symptoms and pressure to be thin and significantly greater reductions in BMI for those with initially elevated eating disorder symptoms. Conclusions: Results indicate that this intervention reduced both eating disorder symptoms and unhealthy weight gain, but suggest it should be improved to produce stronger and more persistent effects, and that it may be useful to target young women with both body image and eating disturbances. (Contains 4 footnotes, 3 tables, and 1 figure.)