The purpose of the present study was to evaluate an intervention to prevent weight gain among households (HHs) in the community. Ninety HHs were randomized to intervention or control group for 1 year. Intervention consisted of six face-to-face group sessions, placement of a television (TV) locking device on all home TVs, and home-based intervention activities. Measures were collected in person at baseline and 1 year. Weight, height, eating behaviors, physical activity (PA), and TV viewing were measured among HH members ages ≥ 12 years. Follow-up rate at 1 year was 96%. No significant intervention effects were observed for change in HH BMI-z score. Intervention HHs significantly reduced TV viewing, snacks/sweets intake, and dollars per person spent eating out, and increased (adults only) PA and self-weighing frequency compared with control HHs. A 1 year obesity prevention intervention targeting entire HHs was effective in reducing TV viewing, snack/sweets intake and eating out purchases. Innovative methods are needed to strengthen the home food environment intervention component. Longer intervention durations also need to be evaluated.