Preventive health services are most effective when provided to large groups, but health care professionals often are limited to provision to individuals or small groups. As recent studies show, the effects of preventive services can be enhanced through the use of community organization, which mobilizes a community's energies and resources to define and address a problem in a way that promotes local ownership and generates increasing effects over time. We pragmatically adapt community organization for health care practitioners. There are three guiding principles: (1) the community of interest must be clearly defined; (2) existing community structures should be used to reach and stimulate community members; and (3) the organizer's role is temporary. We discuss four tactics of community organization: (1) use of community analysis to understand the community; (2) stimulation of community activity; (3) provision of concrete assistance to accomplish community change; and (4) reinforcement of structures that will remain to carry on the programs. Use of these community organization tactics will allow delivery of preventive health services in a way that promotes widespread and lasting effects.