Federal law requires the head of each executive branch agency to develop a plan for achieving a drug-free workplace. The plan must include provisions for identifying illegal drug users through testing on a controlled and carefully monitored basis. No agency is currently responsible for overseeing the implementation of such efforts. A GAO review of agency plans found that employees are subject to drug testing in some but not all Federal agencies. In agencies with drug testing, GAO found disparities in drug testing practices, wide variations in testing costs, and operational problems. Because the head of each executive agency is responsible for implementing a drug testing program, the extent to which Federal employees are required to participate in drug testing and the penalties imposed for drug use primarily depend on the emphasis given to drug testing at the individual agency. This situation has contributed to inequities in the treatment of Federal employees. To standardize drug testing costs and eliminate operational costs across agencies, GAO recommends that the Office of Personnel Management be given the responsibility for drug testing program coordination. An appendix lists the 18 agencies with drug testing programs that GAO included in its review. 3 tables