This paper reviews the history of the placement of mentally retarded students during the first half of this century. In 1900, it was generally assumed that custodial care of feebleminded persons was necessary to protect society. Severely retarded students were regularly excluded from public school attendance. Soon school officials began adopting behavioral management and instructional strategies for coping with students who advanced through the school system more slowly than expected. The schools had achieved nearly universal pupil enrollment, making pupil differences a serious challenge to educators. Not surprisingly, special classes sprang up, and alternative instructional approaches and promotion policies were considered. A perceived need for sorting students encouraged the development of intelligence tests. Though low mental test scores and grades contributed to special placement decisions, teacher judgments always played a large part in making special education assignments. During the 1920's, educators showed increased confidence in intelligence tests and their use for classification. In contrast, the International Council for the Education of Exceptional Children, founded in 1922 by a group of educators, was designed primarily to emphasize the education of the "special child," rather than identification or classification. Though services were being extended, difficulties for special education continued to mount until the dramatic changes of the 1960's. (BW)