Most attention on aviation security since September 11, 2001, has focused on airline passengers, luggage, and carry-on items. At the same time, air cargo security has been relatively neglected. The need for improved security screening guidelines for air cargo was the focus of this research project, which was accomplished through surveys, a case study at an air cargo facility, and computer simulations testing various setups of security technologies to screen cargo within a facility. Information on security measures used for cargo and personnel, as well as the frequency of cargo screenings and information on the size and layout of cargo facilities, was obtained through the survey. A case study was performed at a major U.S. airport to gather data pertinent to the simulations used to test security setups. This information included the frequency of truck arrivals, the number of flight destinations, and security measures in place, as well as the general facility layout. The simulations, conducted in Arena 7.01, tested the effectiveness and cargo throughput of four security cases. Each case used a different combination of security measures proved suitable for an air cargo environment. The security setups were evaluated on the basis of the security systems' costs, the overall effectiveness of catching high-risk cargo, and the average amount of time taken to process cargo through the facility. Government and aviation officials can use this framework as a step toward achieving a well-rounded plan for ensuring the safety and security of U.S. air cargo.