This article reviews recent trends, developments and empirical support for the expansion of psychological practice to include school-based treatment and management of serious and chronic medical conditions, including somatization, in collaboration with primary health care providers. Trends and developments reviewed include (a) the expansion and integration of health, mental health, social and community services in schools, (b) the rapid growth of school-based health centers (SBHCs), (c) psychology's increased involvement in the collaborative treatment of chronic and serious medical disorders, (d) recent federal and state legislative initiatives, and (e) cost-driven marketplace changes. Lack of empirical data specific to collaborative psychologist-health care provider collaboration in schools and SBHCs, particularly around somatization, is discussed. Ethical and Eeg al, professional, and reimbursement issues that must be addressed if psychologists are to practice in this emergent arena are identified. This article calls for research to document both the clinical effectiveness and cost-efficacy of collaborative psychologist-primary care provider intervention in schools and SBHCs. (C) 1999 Elsevier Science Ltd.