Summary: Federal user fees, such as agricultural commodity grading fees, trademark registration fees, and park entrance fees, provided the government with $196.4 billion in revenues in fiscal year 1996--more than twice the amount collected from excise taxes, estate and gift taxes, and customs duties combined. If user fee collections continue to grow, how Congress oversees and federal agencies manage them will become increasingly important. This report identifies 27 agencies for which fees from the public represented 20 percent or more of their funding averaged over fiscal years 1991 through 1996. For these agencies, GAO (1) identifies changes in agencies' reliance on user fees since the passage of the Budget Enforcement Act of 1990 and (2) describes the ways that user fees are structured in the budget, including what budgetary controls govern the availability and use of these fees and how they are treated under the act. GAO also identifies issues for consideration in the future design and management of user fees.