In this article, the author features the Children's Support Services (CSS) project in Lowell, Massachusetts, which is an interagency, multidisciplinary program that provides young children and their families a range of child development, mental health, and family support services. The CSS project, which was begun in September 2000, addresses the needs of preschool-age children who exhibited significant behavioral difficulties. The author describes how the project has proven to be an effective and efficient system of mental health care for urban preschoolers with behavioral challenges who are at risk for academic failure. (Contains 2 tables.)