Potential promises and problems in the placing of children with special needs or handicaps in the regular classroom are examined in this document. The history of mainstreaming, its rationale, and generally accepted definition are outlined. The focus of this report is upon the role of the teacher union in the complex requirements involved in mainstreaming. The positions adopted by the American Federation of Teachers and other educational groups are presented. It is pointed out that the best interests of the children who are placed in regular classrooms despite handicaps are best served when teachers are fully prepared and understand their obligations, responsibilities, and reliable sources of support. (JD)