This chapter discusses the argument of Sections 5-18 of G.E.M. Anscombe’s Intention. It begins by considering Anscombe’s reasons for defining the concept of intentional action according to “a certain sense of the question ‘Why?’”. Following this, the chapter considers Anscombe’s discussion of several ways that this question can be refused application, each of which leads her to introduce a necessary condition of intentional action. Important concepts that are discussed in this chapter include those of knowledge without observation, mental causality, motive, and the relation between causes and reasons for acting. Anscombe’s account of these matters is contrasted in several places with that of Gilbert Ryle, and it is argued, contrary to Donald Davidson, that Anscombe was not in fact an “anti-causalist” about action explanation. The chapter also considers the possibility of doing something intentionally but “for no reason”, or for reasons that one cannot easily identify or express.