This is an exploratory study concerned with understanding the role and experiences of teaching assistants (TAs) within primary schools. The analysis suggests that TAs are constructed within a policy discourse that tends to posit their role as peripheral to teaching and learning. I offer an alternative account, deploying a concept of liminality which acknowledges the creative, open, ambiguous and ambivalent nature of the TA's role. My argument is supported by an interpretation of data drawn from a small qualitative study of TAs within two selected multi-ethnic inner-city schools. It draws attention to the boundary work of TAs, both within schools and between the "inside" and "outsides", the schools and their wider social and cultural contexts, which is important in understanding processes of in/exclusion within schools and the TAs' contributions, both overt and hidden. (Contains 2 notes.)