OBJECTIVES: To determine the effectiveness of a weight-management program with personal counseling by phone or e-mail. METHODS: A randomized controlled trial of a 6-month program comparing two modes of intervention delivery (phone, n = 462; Internet, n = 464) with self-directed materials (control, n = 460), among overweight employees. Change in body weight after 2 years was the main outcome. RESULTS: Among complete cases, weight loss in the Internet group was 1.2 kg (95% confidence interval [CI], -1.9 to -0.4) and in the phone group 0.8 kg (95% CI, -1.5 to 0.03), compared with the control group. Multiple imputation of missing body weight resulted in comparative weight losses of -0.9 kg (95% CI, -2.0 to 0.3) and -0.4 kg (95% CI, -1.4 to 0.7). CONCLUSIONS: Among complete cases, the Internet intervention showed modest long-term weight loss, but among all participants neither program version was more effective than self-help.