This paper explores the implementation of formative assessment through the "autism lens" in order to analyse why the process can be exclusionary for some learners on the autism spectrum. The central thesis of the paper is that, where teachers have no understanding of the autism learning style, they are likely to revert to a normative, "majoritarian" construction of learning. Two problems may flow from this. First, majoritarian assumptions about learning could dominate the inferential process that is the foundation stone of formative assessment. This could lead teachers to mis-read what is going on inside the heads of learners on the autism spectrum, and cause them to make partial and inaccurate inferences about their learning. Second, majoritarian assumptions may also inform the interactive process that underpins formative assessment. Social interaction can be challenging for learners on the autism spectrum and can limit or exclude their participation unless sensitive modifications are made to the social and communication environment. The case is, therefore, made for teacher awareness of a "minoritarian" perspective that foregrounds knowledge and understanding of the autism learning style. Arguably, this knowledge and understanding could enable teachers to adapt the formative assessment process so that it is more effective and inclusive for this group of learners.