The present study examined the conditions and challenges of successfully including adolescent students with mild intellectual disabilities within a mainstream school context. The study was based on qualitative interviews with nine special education teachers who worked in special education groups in lower secondary schools. A thematic structural analysis was performed to identify themes. The need for an overarching inclusive philosophy at school and adequate organizational, social, and academic facilitation were considered essential conditions for successful inclusion. Organizational constraints, inadequate facilitation and a lack of self-confidence among students were identified as challenges. Successful inclusion was found to depend on extraordinary engagement among special education teachers due to a lack of support and commitment in the school organization. The fundamental objectives of the successful inclusion of students with mild intellectual disabilities within a mainstream school context requires a basic monitoring on all levels of the school organization, i.e., management and the entire school staff--including general education teachers. However, students' own experiences and perceptions of inclusion are considered the greatest indicators of success.