The aim of this study was to assess the quality of school integration for disabled students in the Italian state school system, according to two criteria: the mainstream and the special teachers' point of view concerning the disabled students' social and syllabus integration, and the sense of loneliness of the disabled students in their classes. Ninety-one classes in 36 schools in three Italian cities, Padova, Roma and Messina participated in the study. Two different questionnaires were administered to 85 mainstream teachers, 88 special teachers, 102 disabled students and 102 non-disabled students. For the teachers' questionnaires, both special and mainstream teachers showed a positive evaluation of the disabled students' social and syllabus integration. The disabled and non-disabled students showed quite a low sense of loneliness in their classes, although the disabled students showed a higher level of loneliness in their classes. Some factors, e.g. gender, number of disabled students in class, seemed to affect this result. Our results confirm the need to monitor constantly the quality of school integration, and to investigate this process by further research, in order to improve our educational practices with disabled students. (Contains 11 tables and 9 notes.)