This paper reviews and evaluates the literatures on children in families that are homeless and on adolescents who are homeless on their own. After presenting several emerging theoretical approaches, we propose a broad ecological-developmental perspective that recognizes that, although persons in these groups often lack resources and experience negative events that can amplify the risk for poor outcomes, they also have resources and adaptive potential. The perspective also recognizes that homelessness may have different meanings and outcomes at different points in development and that we need to consider interactions between individual development and multiple levels of social organization in order to foster new solutions to homelessness. On the basis of this perspective, we discuss directions for treatment and preventive interventions as well as social policy.