The aim of this study was to examine teachers’ attitudes towards inclusion of children with disabilities in the educational system, to determinate the sources of their satisfaction and dissatisfaction in working with these students and to analyze suggestions for improving the quality of inclusion. The study included 150 class and subject teachers from 12 primary schools in Zagreb. Participants filled in the Croatian version of the Questionnaire of attitudes about inclusion SINKL 2.0. Results of quantitative analysis showed that teachers assess relatively low their professional qualifications for working with children with disabilities. In addition, there was a statistically significant difference between class and subject teachers on subscale of professional support, in which subject teachers evaluate than support as better. Also, teachers who have no special needs educational assistant estimate significantly higher problems in inclusive classes. Qualitative analysis of the responses regarding the satisfaction about the work with students with disabilities showed that the most common categories are the progress of students, awareness of other children in the class about the diversity, good cooperation with parents and professional services, while the most common sources of dissatisfaction are the unrealistic expectations of parents, insufficient training of teachers to work with children with disabilities and the lack of time they have for them. The dominant categoriesof the proposals for the improvement of the quality of inclusion are frequent training and professional development of teachers, obligatory professional associates in schools, better involvement of the entire system to support and assist teachers in working with students with disabilities, mandatory trained special needs teaching assistants and better equipment of schools.