The bulletin explores various aspects of mainstreaming handicapped youngsters into regular K-12 social studies classrooms. It is intended to give classroom teachers practical advice on dealing with the problems which have resulted from the passage of Public Law 94-142. Major problems include that handicapped youngsters often present an additional burden to already overworked teachers and that mainstreaming is sometimes contradictory to tasks to which teachers give higher priority. The bulletin is presented in 11 chapters. Chapters I and II define mainstreaming and explain the philosophy behind it. Mainstreaming provides the maximum degree of participation and inclusion for handicapped students so that they can profit from a regular classroom environment according to their ability. It was developed to extend civil rights to the handicapped and to make school more reflective of society. Chapters III, IV, and V discuss various modes of instruction used in mainstreaming classes including individualized instruction, involving resource teachers, developing student-centered activities, and grouping. Chapters VI through X suggest how to organize and present social studies content in a mainstreamed class, review mainstreaming practices currently in use, explain how to involve community organizations and teacher training institutions in the mainstreaming process, and offer a prologue for mainstreaming's future. The final chapter lists sources of additional information regarding mainstreaming. (DB)