Many organizations are making focused efforts to prevent obesity. To achieve their goals, accelerate their progress, and sustain their success, the assistance of many other individuals and groups-not all of them with a singular focus on obesity prevention-will be essential. In October 2011 the Institute of Medicine held a workshop that provided an opportunity for obesity prevention groups to hear from and hold discussions with many of these potential allies in obesity prevention. They explored common ground for joint activities and mutual successes, and lessons learned from efforts at aligning diverse groups with goals in common.