With the increasing number of teaching and classroom assistants across the UK there is now much debate about what their role should be. In particular concerns have arisen about the extent to which they overstep the boundary from supporting teaching and learning into teaching pupils. This study assesses this issue within Scotland. It draws on a national survey of 2000 head teachers, teachers and classroom assistants and interviews with directors of education in nearly half of all Scottish local authorities. Findings from the research suggest a small number of classroom assistants in Scotland are overstepping the boundary into teaching. The paper concludes with an explanation as to why this is happening taking into account aspects such as local authority policy, school size and the individual characteristics of the classroom assistants.