We audited the Transportation Security Administration’s (TSA) Screening of Passengers by Observation Techniques program. The program’s intent is to screen passengers by observing their behavior in order to detect potential high-risk travelers. This program uses Behavior Detection Officers to detect passenger behaviors that may be indicative of stress, fear, or deception. Congressman Bennie Thompson requested an audit of TSA’s Screening of Passengers by Observation Techniques program to determine its effectiveness, efficiency, and economy as a security screening protocol at airports. The audit objective was to determine whether TSA’s Screening of Passengers by Observation Techniques program is structured to ensure that passengers at U.S. airports are screened in an objective and cost-effective manner to identify potential terrorists.