The deployment of Teaching Assistants (TAs) to support learning has been the subject of much critical debate, including the particular concern that TAs too often becomes a less skilled replacement for the teacher rather than acting as an additional source of support. Despite efforts to encapsulate the TA's contribution to learning within specific models of deployment, wide variations in practices make the role and its contribution to learning difficult to define. Drawing on data gathered in four secondary schools in England, this paper explores TA deployment practices through six typologies that provide an opportunity to explore the relative contributions of the TA and where applicable, the teacher, "in situ": The Island; The Container; The Separate Entity; The Conduit for Learning; The Partner and The Expert. Illustrated graphically, these bring key elements together in a more contextualised and dynamic way. The paper concludes that the spatial and relational dimensions of deployment warrant more nuanced treatment and that more emphasis on partnership and mutuality and rather less on difference and hierarchy might be productive.