To be eligible for special education services under the IDEA, a student must first be found to meet the criteria for at least 1 of 13 recognized disabilities (or the counterpart categories in state law). The second criterion is that the student must be found to require special educational services. A student who needs special education is also entitled to receive related services—that is, other services that enable him or her to benefit from special education. States and school districts must provide each such student with a free, appropriate public education.
This means that not all students with disabilities are eligible to receive services under the IDEA. They must demonstrate educational need. Even those who do not qualify for special education, however, are protected by Section 504 of the Rehabilitation Act of 1973 and by the ADA (1990), which entitle them to reasonable accommodations in school activities to permit them to overcome impairments in one or more major life activities. The number of students in this category is not known.1 Nevertheless, the legal rights accorded them could affect large-scale assessment programs, especially those with high stakes for individual students, by increasing the number of students receiving accommodations and raising questions about the extent to which the scores of students with disabilities should be aggregated with other students' scores.
Educating One and All describes the provisions of the IDEA designed to ensure the fair, nondiscriminatory use of tests in identifying students who qualify for special education services (National Research Council, 1997:69–70):