Summary: The Environmental Protection Agency (EPA) provides millions of dollars to grantees to conduct research, demonstrate pollution control techniques, and perform other activities. Oversight of this large pool of grantees has proven to be difficult. EPA's post-award grant management policy provides few guarantees that unallowable costs for nonprofit grantees will be identified. Identifying such costs is important for effective oversight of EPA's nonprofit grantees. EPA's on-site grantee visits could provide agency officials with a valuable opportunity to test for unallowable costs while they are testing the adequacy of the grantees' financial and administrative systems. Although more time may be required to test for unallowable costs and additional training may be required for regional personnel, the tests would provide greater assurance that grant funds are spent in accordance with Office of Management and Budget (OMB) requirements. The single audit is an important tool for ensuring that federal funds are properly spent. EPA has taken several steps to identify grantees that need a single audit, but it is difficult to identify them definitively because information on total federal expenditures by each grantee is unavailable. As a result, EPA is using other information sources to identify grantees that are required to have a single audit. One of these sources is the Federal Audit Clearinghouse Internet site. This source could be used more effectively if EPA officials were better trained in using the site.