This study analyses the attitudes of teachers in Spain towards the inclusion of learners with autism spectrum disorder in mainstream education settings and their relationship with the perceived benefits of inclusion. The ex post facto prospective design included 180 teachers from 14 schools. Data were collected using a questionnaire on teachers' attitudes towards inclusive education and a second questionnaire on the benefits of inclusion developed for the specific purposes of this study. The results show teachers' positive attitudes towards inclusion as well as the benefits perceived. This study demonstrates the fundamental role of teachers' previous experience. Implications for inclusive cultures and practices in schools are discussed.