Research has examined teacher attitudes, knowledge, and stigma towards inclusion of autistic children in mainstream schools. Less focus has been given to these beliefs among parents. This is problematic as parents are important in the implementation of inclusion and fostering a positive school environment. The current study examined differences in autism attitudes, knowledge, stigma, and inclusive education attitudes (core perspective; expected outcomes; classroom practices) among parents with and without an autistic child; The study also investigated whether autism knowledge, attitudes and stigma predicted inclusion attitudes. 185 parents in the UK (52% had an autistic child) completed questionnaires measuring these variables. Parents of an autistic child had significantly higher core perspective inclusive attitudes than parents without an autistic child. However, this group also reported more beliefs that parents of autistic children are stigmatised. For all parents, core perspective inclusive attitudes were predicted by autism attitudes and stigma towards parents of autistic children. Predictors of expected outcomes and classroom practices inclusive attitudes differed between groups. Findings highlight the need for parental attitude research to be disability-specific and consider different aspects of inclusive attitudes. Parent education to enhance inclusive attitudes should be tailored for distinct parent groups and contact interventions should be considered.