At the population level, turning the tide on obesity requires not only health education and promotion programs, but also systemic changes in our society. However, few of these changes can be implemented by single agencies or organizations acting in isolation. Broader community-driven efforts are needed to advance and maintain systematic changes across multiple settings. We introduce 2 promising approaches for local action to achieve changes: coalition action and community organizing. Understanding differences between the two approaches makes it clear that while each has distinct advantages, there are also possibilities for synergies between them. We also clarify how community-driven efforts can be catalyzed and supported, and describe our efforts as part of the Wisconsin Obesity Prevention Initiative to identify and implement best practices for building and sustaining the necessary local community capacity to carry out systematic changes. We are working with communities to launch initiatives in which residents are engaged through grassroots organizing, and local agencies, businesses, and other institutions are engaged in pursuit of collective impact on obesity prevention. This will allow us not only to compare the effectiveness of the 2 types of initiatives for driving local changes, but also to explore the potential for the two to work together in pursuit of systemic changes for preventing obesity.