Any account of social action presupposes an ontology of action whether this is made explicit or not. This chapter reviews the problem of defining and analyzing action in interaction, and to propose a solution. It describes three dimensions of contrast in the analysis of action. A first point is that both purposive action and non-intentional effects can be seen as ways to do things with words but, as we shall see, they differ in many respects. Second, there is a need to distinguish explicit from primary in action. And third, one can need to distinguish between the constitution of action, on the one hand, and the ex post facto description of action, on the other. The chapter describes the components and types of action in interaction. It discusses two case studies: how it is that actions are recognized and thereby consummated, both by participants in social interaction and by analysts.