This paper reports on a study conducted to assess the health care needs of foster children in California. To evaluate foster children's mental health problems and the services provided to meet them, 154 program administrators, social workers, foster parents, and health care providers were interviewed in 14 counties. Foster parents and social workers were interviewed in groups, and foster parents and administrators also completed questionnaires. We found that although all counties care immediately for children who are injured, abused, or ill, only one county performs routine mental health evaluations of all children, and in most counties less than a third of children ever receive such evaluations. Informants identified mental health problems as more severe than medical problems in this population, and they identified four major barriers to access to appropriate therapy. Recommendations are that all children should receive comprehensive mental health evaluations, and procedures for immediate and ongoing care with consistent providers who are sensitive to foster children's needs should be included in case management plans, and covered by improved payment mechanisms. Additionally, communication, coordination and joint planning should be instituted among relevant agencies to address foster children's needs, and increased resources and training should be directed towards social service agencies and foster parents.