<br.Public health social work is an interdisciplinary, epidemiologically oriented approach to improving human health and well-being. About one quarter of all social workers in the United States currently work in medical or public health settings, a number that is expected to increase significantly in coming years. This handbook, written and edited by respected leaders of the Social Work Section of the American Public Health Association (APHA), describes the rapidly expanding roles of public health social workers as these two disciplines continue to join forces.