The purpose of this qualitative study was to identify characteristics of teachers who were successful in social mainstreaming of students with special needs. In the exploratory stage, several successful teachers were interviewed about their pedagogical beliefs and mainstreaming practices. Themes and categories were extracted. In the major phase 24 teachers and 782 students participated. Based on sociometric measures administered in all classrooms, six successful teachers in social mainstreaming and six unsuccessful teachers were identified. Semistructured interviews similar to those used during the exploratory stage were conducted. Statistical analysis revealed significant differences between the two teacher groups regarding their pedagogical orientation (i.e., relationships with students and with parents), attitude toward inclusion, daily practices (consultation) and personality characteristics (self-efficacy, sensitivity). Implications for teacher preparation and professional development are discussed. (Contains 3 tables.)