State Department's (State) Bureau of Diplomatic Security (DS) is responsible for the protection of people, information, and property at over 400 foreign missions and domestic locations. DS must be prepared to counter threats such as crime, espionage, and passport fraud, technological intrusions, political violence, and terrorism. This report assesses: (1) how DS's mission has evolved since 1998; (2) how its resources have changed over the last 10 years; and (3) the challenges it faces in conducting its missions. The auditor analyzed DS data; reviewed relevant documents; and interviewed officials at several domestic facilities and 18 international missions. Includes recommendations. Charts and tables.