This one-page abstract, was derived from document abstracts listed in "Research on the Effectiveness of Mainstreaming," an ERIC Computer Search Reprint containing bibliographic information and abstracts on more than 120 studies. In the studies reviewed, the role of regular and special education teachers is identified as critical to the success of mainstreamed students. Also identified are the organizational resources, cooperation, and coordination required to support the teachers in their efforts. In this summary, the studies are discussed in six categories: (1) criteria for integrating students into regular classes; (2) the social integration of mainstreamed students; (3) the perceptions and attitudes of parents, mainstreamed students and their peers, and educators; (4) assessments of preservice and inservice teacher training and training needs; (5) organization of the environment; and (6) the effects of mainstreaming on achievement. A list of 41 footnotes concludes the paper. (JDD)