Despite the passage of P.L. 94-142, the climate for acceptance of mainstreaming has changed very little. Contributing to this slow progress is confusion about the skills needed by the personnel involved in mainstreaming. A review of representative literature revealed limited, though significant, research outlining the competencies needed by regular education and special education teachers, the changing role of special education teachers, and the interfacing of competencies needed by educational personnel in regular and special education. Results of the studies reported in this paper provide direction for future action in comprehensive preservice and inservice teacher education.