What is the difference between firing a gun and the gun going off in your hand? What makes one an intentional action of yours and the other a mere happening - is the difference in their causes, in their purposes, or in the reasons behind them? Can actions be explained in the same way as mere happenings, or is there something special about the way we explain one another's actions? What kind of mind must a creature have if it is to be an agent? Can groups of human beings comprise a single agent that performs intentional actions? Such questions about the nature of intentional action and its explanation, the nature of reasons and agents are at the heart of philosophy of action. This wide-ranging and accessible introduction to contemporary debates guides the reader through the major views and arguments with the help of examples drawn from everyday life.