The initial response to homelessness in the United States has focused on stop and go measures to address the dire need for emergency food and shelter, and then on providing additional assistance to homeless persons to help them move out of homelessness. New preventive measures to help people avoid becoming homeless have largely been ignored. But now that efforts to provide emergency food and shelter are well under way throughout the country, many more experts, policymakers, and service organizations have begun focusing on homelessness prevention. Nevertheless, actual prevention efforts are still tentative and somewhat haphazard. In support of a more rapid expansion of effective homelessness prevention activities, this paper discusses the benefits of prevention, develops an initial framework for a comprehensive homelessness-prevention strategy, and, using this framework, evaluates existing prevention efforts and suggests new initiatives.