The word ‘entrapment’ has three common usages in legal discourse. First, it is used in connection with acts of entrapment: it applies, at least, to a class of acts in which a party, whom we call the ‘agent’, intentionally brings it about that another party, whom we call the ‘target’, performs a distinct act that is of a criminal type. Secondly, it is used to refer to a method of proactive law enforcement: the use of acts of entrapment to secure convictions. Thirdly, it is used, predominantly in the USA, to refer to the entrapment defence: under this usage, it is argued that the offence with which the defendant is charged resulted from an act of entrapment. In most jurisdictions, and in the literature, the focus has been, as it is here, on acts of entrapment, called ‘legal’, ‘state’, ‘government’ or ‘police’ entrapment, in which the agent is, or is a deputy of, a law-enforcement officer. We mention entrapment by other agents, called ‘civil’, ‘non-state’ or ‘private’ entrapment, only in passing.