Summary: Pursuant to a congressional request, GAO reviewed the Centers for Disease Control and Prevention's (CDC) programs and activities, focusing on: (1) the appropriateness of CDC programs given its mission; and (2) possible program duplication between CDC and other Public Health Service (PHS) agencies. GAO found that: (1) CDC has broad legislative authority to protect public health by preventing and controlling chronic diseases and injuries; (2) CDC has been involved in programs addressing chronic disease, vaccinations, and unintentional and intentional injuries, some of which predate legislation that established specific programs; (3) CDC has used behavioral interventions as a means of controlling and preventing disease and injury; (4) CDC carries out its activities through its multidisciplinary technical staff and its longstanding relationships with state and local health departments; (5) CDC provides state and local health departments with grants and technical assistance to support their public health activites; (6) the national health community regards CDC as the leading prevention agency and believes its programs are appropriate to its mission of protecting public health; (7) there is no apparent duplication of program activities with other PHS agencies even though the activities are similar, since the activities are not directed to the same target population for the same purpose; and (8) PHS agencies generally avoid duplication through formal and informal coordination and collaboration.