Education is important for all children, but even more so for children with disabilities, whose social and economic opportunities may be limited. In this article, Laudan Aron and Pamela Loprest assess how well the nation's education system is serving students with disabilities. Aron and Loprest trace the evolution of the special education system in the United States from its origins in the civil rights movement of the mid-twentieth century. They note the dual character of federal legislation, which both guarantees eligible children with disabilities the right to a "free, appropriate public education in the least restrictive setting" and establishes a federal funding program to help meet this goal. They then review the types of services and accommodations these children receive from infancy through young adulthood. The special education system has given children with disabilities much greater access to public education, established an infrastructure for educating them, helped with the earlier identification of disabilities, and promoted greater inclusion of these children alongside their nondisabled peers. Despite these advances, many problems remain, including the over- and underidentification of certain subgroups of students, delays in identifying and serving students, and bureaucratic, regulatory, and financial barriers that complicate the program for everyone involved. More important, the authors show that special education students still lag behind their nondisabled peers in educational achievements, are often held to lower expectations, are less likely to take the full academic curriculum in high school, and are more likely to drop out of school. Only limited evidence is available on the effectiveness of specific special education services or on how to improve student achievement for this important subgroup of students. Improving the system will require better ways of understanding and measuring both ends of the special education continuum, namely, what services special education children need and receive, and what academic outcomes these students achieve. Without stronger evidence linking these two aspects of the system, Aron and Loprest argue, researchers will be unable to gauge the efficacy of the services now being delivered or to formulate effective reforms to the system as a whole. (Contains 59 endnotes and 3 figures.)