Complementary and alternative medicine (CAM) is a group of diverse medical and health care systems, practices, and products that are not presently considered a part of conventional medicine. There are three general types of CAM: (1) Western alternative medical therapies, (2) traditional medical systems, and (3) complementary approaches. Researchers estimate that 68% of U.S. adults will use at least one form of CAM in their lifetime. Research and policy initiatives in CAM are growing in response to the widespread use. This entry discusses definitions and utilization of CAM, public policy with regard to CAM, and the relationship between CAM and public health. It also examines challenges for research on CAM; concerns related to reimbursement, credentialing, and education; legal and ethical issues; and the need for ...