In somewhat of a contrast, the education of the developmentally delayed or behaviorally impaired was still more a function of social management. Mentally retarded children in Pennsylvania could be removed from their families to private schools pursuant to an 1852 appropriation, and in New York early public school classes for “unruly boys” (begun in 1871) served only to segregate “problem” children from the mainstream and made no attempt to remediate learning difficulties.
     By the early twentieth century, more emphasis was placed on effective education for the disabled, as evidenced by the passing of mandatory special education laws in New Jersey, Massachusetts, and New York. In 1915, Minnesota was the first state to enact special education teacher certification requirements, and Pennsylvania and Oregon instituted intrastate cooperative agreements for meeting the needs of educationally exceptional students. However, during the 1930s this trend was significantly curtailed by the Great Depression. It was not until the 1970s that scientific and pedagogical advances and the expansion of civil rights theory combined to literally rewrite the very definition of the education of the disabled.
     Building directly on the Supreme Court’s 1954 decision Brown v. Board of Education of Topeka, Kansas, coalitions of advocacy groups for the disabled turned to the federal courts for recognition and definition of special education rights. They primarily based their claims on the equal protection and due process clauses of the U.S. Constitution, the same legal mandates that had ended “separate but equal” education based on race. In two landmark decisions, Pennsylvania Association for Retarded Children v. Commonwealth of Pennsylvania (1971) and Mills v. Board of Education of the District of Columbia (1972), the concept of the education of the disabled was redefined. Under the equal protection clause (Pennsylvania Association) and the due process clause (Mills), the federal courts recognized the fundamental right of each disabled child in America to attend school, to receive individual educational services at least equivalent to those enjoyed by nondisabled students, and to not be denied educational services without the right to contest that action through due process of law.

Those two Court cases led directly to the Education of All Handicapped Children Act in 1975, which eventually was retitled the Individuals with Disabilities Education Act (IDEA). For the first time, the following components were identified nationwide as prerequisites for the appropriate education of the disabled:

1. A broad definition of educational disability. Basing its drafting on the input of current scientific and educational disciplines, the federal government greatly expanded its definition of educational disability. The traditional categories of physical disabilities were retained, but now the great majority of children identified as disabled were those with processing, executive, and affective disorders, such as specific learning disabilities (the category that accounted for nearly half of the six million identified disabled students in 1999); emotional impairment; receptive and expressive language disorders; autism spectrum disorders; and attention deficit disorders.
2. Zero reject. The education of the disabled is premised upon the belief that all students can benefit from education, that none are so disabled that services should not be provided.
3. Free appropriate public education (FAPE). The provision of FAPE to all disabled students is mandated in the IDEA and requires that education and related services (such as speech therapy, occupational therapy, and counseling) be provided at no charge to the parents of the students through public or privately contracted programs implemented by an individualized educational program.
4. The individualized educational program (IEP). Since 1975, IEPs have formed the foundation upon which education is provided to the disabled. A paper program drafted through a cooperative effort of parents and school staff, the IEP is individualized for the particular special education student and forms a contract between school and family as to the provision of specific services.
5. The least restrictive environment. Founded upon constitutional principles, the education of the disabled is to be provided in the least restrictive environment. Since the goal of the education is for the student to be able to become a productive citizen within the greater society, removal of the student from the mainstream school experience is only to occur if necessary for appropriate instruction.