Since the early 1990s, Congress has supplemented the Department of Education's (Education) Impact Aid program by providing funds for the Department of Defense's (DOD) Impact Aid program to compensate school districts with a high number of military dependent students. The National Defense Authorization Act for Fiscal Year 2010 required GAO to review the use of these funds. GAO reviewed (1) what is known about the utilization and effectiveness of DOD Impact Aid funds, (2) the challenges faced by school districts in serving military dependent students, and (3) how DOD and Education have collaborated on their assistance. To address these issues, GAO conducted a Web-based survey of all 154 school districts that received DOD Impact Aid in any year from 2001 to 2009, with a response rate of 77 percent. GAO also interviewed officials from DOD and Education and seven school districts in five states, ranging in school district size, location, and percentage of military dependent students. The findings from these visits cannot be projected nationwide, but illustrate valuable perspectives. GAO recommends that the Secretary of Education determine whether to require school districts to report data on the academic outcomes of military dependent students, and if so, to determine the need for any additional legislative authority. Education agreed with GAO's recommendation, and DOD provided oral concurrence. Appended are: (1) Objectives, Scope, and Methodology; (2) Information on Additional Mandate Provisions; (3) The 13 Objectives from Education and DOD's MOU; (4) Comments from the Department of Education; and (5) GAO Contact and Staff Acknowledgments. (Contains 2 tables, 7 figures, and 42 footnotes.)