The number of pupils with autism spectrum disorder (ASD) who join mainstream schools in the UK has been increasing over the last decade. Given the difficulties in social and emotional understanding which these children have, their inclusion in schools is likely to be challenging. Their ASD-related manifestations, moreover, tend to allow for tensions to arise between them and the different systems of the school ecology. We examine the inclusion of these pupils from a developmental-systems perspective as articulated by the bio-ecological and the transactional models. Using data from a qualitative research project which explored the effect of autism-related difficulties in social and emotional understanding on the inclusion of 17 pupils with ASD the study describes the working dynamic of the arising tensions at the micro-system level. The study outlines an ecopmap of the nested structures at the micro-, meso-, exo-, macro- and chrono-systems which may facilitate or impede the children's inclusion.