How does the participation of students with special educational needs (SEN) in mainstream education affect their social inclusion? We introduce a single-item pictorial measure, the Inclusion of Other in the Self (IOS), to compare the social inclusion of SEN students attending mainstream regular schools to social inclusion of SEN students attending special schools. We collected responses from 138 parents of SEN students aged 4-20, to obtain data on the loneliness, friendships and social inclusion of SEN students. The parents of SEN students attending regular schools did not perceive their children to be less included than parents of SEN students attending special schools. School context decreased SEN students' perceived loneliness independent of the school type. And while most SEN students' friendships were formed at school, SEN students attending regular schools had more friends, and these were more likely to live in the same neighborhood. Overall, the social inclusion of SEN students across school types was not affected by the school type, only by the school's inclusive characteristics.