Inclusion of autistic pupils into mainstream schools is common practice and staff should have adequate knowledge on teaching and managing classroom behaviour. However, autism knowledge among teaching staff may be inconsistent. A mixed-methods design examined differences between school staff in autism knowledge, perceived barriers to inclusion and required support. 138 early years staff, school teachers and pupil support assistants took part. Knowledge and experience were assessed using Knowledge about Childhood Autism among Health Workers questionnaire (KCAHW; [Bakare, M. O., P. O. Ebigbo, A. O. Agomoh, and N. C. Menkiti. 2008. Knowledge about childhood autism among health workers (KCAHW) questionnaire: description, reliability and internal consistency. Clinical Practice and Epidemiology in Mental Health 4 (1): 17]). Qualitative measures addressed perceived barriers to inclusion and recommended supports. Significant differences in the knowledge of autism scores were shown.. Similar themes were identified across all staff, with five themes reflecting barriers to inclusion (Knowledge, Support, Training, Management of ASC features and Parent involvement) and four themes relating to required support (Individualising educational experience, Changes to learning spaces, Opportunities to learn about ASC and Communication). Government inclusion policy should take a whole school approach and consider staffs' actual and perceived barriers to inclusion of autistic children.