Summary: GAO reviewed the Bureau of Prisons to determine whether it had made overpayments to contractors. During fiscal year 2001, the Bureau of Prisons had 24 open construction contracts that totaled about $1.9 billion. In addition to general disbursement controls, GAO found internal controls specific to construction contracts in which both the project representative and the contracting officer must approve each monthly progress payment invoice. GAO sampled 27 payments on five construction contracts to determine if construction contract payment controls were properly designed, in place, and operating to prevent or detect overpayments. GAO found that the internal controls were in place and operating and construction contract payment amounts were correct, or, if errors occurred, they were detected and corrected promptly as a normal part of the payment system. A few minor clerical errors were subsequently detected and corrected by the Bureau of Prisons through its own routine control procedures before GAO made its review. GAO concludes that the risk of undetected construction contractor overpayments at the Bureau of Prisons appears to be small.