In this article I will discuss the potential that activity theory offers for analysing and rethinking collaborative practice in schools. The purpose of this article is to argue that activity theory provides an important perspective on the problem of developing practices which are frequently observed to be desirable but remain difficult to develop. I suggest that activity theory directs attention to points of intervention that might not otherwise be considered. The article argues that there is a need for the development of the theory itself if its analytical potential is to be realized.