The General Accounting Office (GAO) was requested by the Senate Committee on Commerce, Science, and Transportation and its Subcommittee on Aviation to examine the causes of screeners' problems in detecting dangerous objects and the efforts of the FAA to address these problems, as well as the screening practices of selected foreign countries and the potential for using these practices to help improve screeners' performance in the United States. As part of its regulatory oversight of the screening operations, the FAA tests screener's ability to locate test objects placed in carry-on baggage or hidden on a FAA agent's person. The agents use standard test objects, such as guns, during these compliance tests, and the FAA can fine an airline if an object is missed. The FAA also tests screeners by using more sophisticated simulated bombs that are more difficult to detect. Concerns have long existed over screeners' performance in these tests. In 1978 screeners failed to detect 13 percent of the objects during compliance tests; and in 1987 screeners were missing 20 percent of the objects during the same type of test. Since 1997, the FAA has designated data on tests results as sensitive security information. Consequently, more recent data on test results cannot be released publicly and are discussed in a separate, limited-distribution report; nevertheless, the FAA acknowledges that screeners' performance in detecting dangerous objects during its testing is not satisfactory. Long-standing problems combine to reduce screeners' effectiveness in detecting dangerous objects, most notably the rapid turnover of screener personnel and human factors conditions that have for years affected screeners' hiring, training, and working environment. A key factor in the rapid turnover is the low wages screeners receive. The FAA is pursuing several initiatives to improve the hiring, training, and testing of screeners; to increase their alertness and more closely monitor their performance; and to certify the security companies that air carriers retain to staff screening checkpoints. Most of these efforts, however, are behind schedule. Passenger screening the GAO were similar to those in the United States, although tests indicate that screeners' performance in some of these countries is better than in the United States. Since the FAA has already begun several efforts to improve screeners' performance, the GAO is not making recommendations to revise current screening practices in the United States. 2 tables