This paper addresses the participation of students with autism spectrum disorders (ASD) in mainstream schools. There are different benefits for ASD students to be educated in an inclusive environment (Gena, 2006; Whitaker, 2004). They challenge the school community by presenting difficulties in essential domains for school activities (Chamberlain, Kasari and Rotheram-Fuller, 2006; Eman and Farrell, 2009; Humphrey and Symes, 2010). Thus, these are students with increased difficulties participating in inclusive environments, reinforcing the need of an adequate inclusion process (Gena, 2006; Hall and McGregor, 2000; Hestenes and Carroll, 2000). We characterised this students' participation with a questionnaire to the students from mainstream classes in which ASD students were included, a questionnaire applied to each class teacher/head teacher and an interview to four of the school educational assistants. The location of the ASD student in mainstream classroom was also analysed, trying to understand if it influences the quality of ASD students' participation, hypothesising that there is an influence. Results showed a good perception of the students with ASD and their behaviour, low frequency of behaviours involving interaction with these students, good feelings about their presence at the school/class and an overall acceptance of them in the peer groups of typical development students. Results are mostly consistent across the different information sources. We found a significant effect of the location on the quality of participation. Results are mainly consistent with the literature reviewed and enlighten the need to keep making progress on inclusion practices related to ASD students in mainstream schools. [Paper presented at the Inclusive and Supportive Education IV Conference Congresso Internacional da Pró-Inclusão (8th, Lisbon, Portugal, July 26-29, 2016).]