The federal government manages about 650 million acres, or 29 percent, of the 2.27 billion acres of U.S. land. Four land management agencies--the Bureau of Land Management (BLM), the Fish and Wildlife Service (FWS), the National Park Service (NPS) in the Department of the Interior (Interior) and the Forest Service, in the Department of Agriculture--manage about 95 percent of these federal acres. Interior's Bureau of Reclamation (BoR) manages another 1 percent of these acres and focuses on water projects. The five agencies collect certain data to help manage these federal lands. GAO was asked to review whether the five agencies collect certain federal land and resource data (referred to as data elements), how these data elements are stored, and their potential reliability. GAO included over 100 data elements at each agency in its analysis that can be categorized as information on (1) federal land and the resources the five agencies manage, (2) revenues generated from selected activities on these lands, and (3) federal land subject to selected land use designations. GAO assessed the potential reliability of data elements collected by the agencies generally for fiscal years 1996 through 2009 based on a survey of agency officials and a review of available audits and evaluations. GAO did not collect data for each data element. GAO is making no recommendations in this report.