Law enforcement officers (LEOs) within the federal government play a key role in maintaining the safety and security of federal property, employees, and the general public. In this report, we describe the number of LEOs that federal civilian law enforcement components employed as of June 30, 2006; the federal job series classifications the components used to employ LEOs; and the sources of their primary legal authorities. To identify federal components that employ LEOs, we consulted, among other sources, the Federal Citizen Information Center's Cabinet Agencies and Independent Agencies and Commissions Directory; a list of organizations included in the Federal Law Enforcement Training Center (FLETC) 2004-2005 List of Agencies Trained at FLETC; and federal agencies listed in Federal Law Enforcement Officers, 2002, published by the Department of Justice's Bureau of Justice Statistics (BJS). We identified 104 federal civilian law enforcement components and administered two Web-based surveys to each--one survey on the primary authorities and the other survey on the job series classifications. We defined an LEO as an individual authorized to perform any of four specific functions: (1) conduct criminal investigations, (2) execute search warrants, (3) make arrests, or (4) carry firearms.