Summary: The Federal Acquisition Streamlining Act of 1994 allows the use of performance-based payment (PBP) as an alternative to other forms of contract financing. According to the Department of Defense (DOD), the paying office processed about one million invoices for 363,000 major contracts. In fiscal year 1999, only 195 of these contracts contained performance-based provisions. These contracts are so few in number because they are a relatively new form of contracting within DOD. In November 2000, however, DOD indicated that performance-based financing will be military's preferred contract financing method for future fixed-price contracts. This report reviews the C-17 aircraft production program as a case study of the business processes used to make investment expenditures during the production phase of a major weapons system. GAO chose this contract because it is mature, stable, and is performance-based rather than cost-based. GAO found internal control weaknesses in the C-17 program affecting compliance with regulations, policies, and procedures over (1) establishing withhold amounts by the Air Force contracting officer for conditionally accepted items, (2) processing by the Administrative Contracting Officer for performance-based payment requests, (3) processing by the Administrative Contracting Officer of invoices for delivered aircraft, and (4) processing of a delivery payment by the paying office at the Defense Finance Accounting Service Columbus Center on a contract containing performance-based payment provisions.