Nearly 6.5 million students in the United States ages 3 through 21 are currently classified as requiring special education. Those students have physical, developmental, and emotional disabilities that make educational endeavors more challenging for teachers, administrators, and the students themselves. Yet historically, the needs of special education students were met sporadically if at all. Parents were frequently left to fend for themselves and their children within the education system. In the 1960s, the federal government made a historic entrée into the field as part of the Great Society initiatives, launching a legislative effort that would ultimately become the Individuals with Disabilities Education Act (IDEA). Special education students' rights were won through political and courtroom battles that resulted in the establishment of laws and principles protecting all students with disabilities. Today, the law governs states' obligations to students with special needs and defines the federal role in providing services to those children. All students with disabilities are guaranteed the right to a "free appropriate public education" in the "least restrictive environment" possible. Ninety-five percent of all children ages 6 through 21 served under Part B of IDEA spend at least some portion of the school day in regular classrooms, and nearly 60 percent of those students are in mainstream classes for at least 80 percent of the day. By many measures, the law has been a success. There is, however, another looming component to federal special education law that cannot be ignored: finance. This report presents a detailed analysis of federal special education finance data for more than 9,000 school districts across the United States. It suggests that the stated priorities of the federal grants to states--population- and poverty-based funding--are often abandoned in light of certain other provisions of the formula. Meanwhile, federal formulas grow further from states' realities every year. Lawmakers continue to spend $11.5 billion annually on special education in accordance with the outdated formula (and states and school districts spend much more). With the passage of time, a relatively minor problem has become a large one. As Congress begins to consider reauthorization of the law, it is in an entirely different context. A persistent recession, public concern about the national debt, and a growing focus on accountability for federal funds will demand that lawmakers prioritize efficiency of spending above all else. To fulfill their historic promise to student with disabilities and their families, lawmakers must modernize the critical funding mechanisms that help educate students whose needs have never been greater.