Defining “community” from a research perspective is difficult. Communities consist of environmental, social, and geographic components. In addition, race, ethnicity, socio-economic status (SES), and group memberships often play roles in community identity. Barry Wellman and Scot Wortley urge that to truly understand and influence a community, and most certainly to conduct research within communities, one must take into account the varied nature of relationships and networks and how they may work together synergistically to meet the needs of community members. Using the Social Ecological Model, with its delineation of multiple spheres of influence (individual-interpersonal-organizational-community-public policy), community-based research has attempted to reach this understanding. Although dramatic shifts have not yet been realized, many studies suggest improved health behaviors and healthy environments, which indicate a promising future for community intervention work. The discussion that follows reviews the theory and rationale for community-based interventions, the socialecological approach to understanding and studying obesity, and the progress and promise of community interventions.