I argue that while every betrayal is a breach of trust, not every breach of trust is a betrayal. I defend a conception of trust as primarily a feature of behaviour (i.e. trusting behaviour) and only secondarily a feature of a mental attitude. So it is possible to have the attitude of distrust towards someone while still trusting them in the way you behave. This makes sense of the possibility of Judas Iscariot breaching Jesus’ trust, and so betraying him, even (...) though Jesus presumably knew that Judas would do just that. This conception of trust may be spelt out in terms of making oneself reliant on somebody in a collaboration with them. Such collaborations include relationships like friendships and love affairs, as well as political activities or defending one’s country against aggression. I argue that only when these collaborations involve a commitment to loyalty is a breach of trust a betrayal. And loyalty is a feature of those collaborations or relationships that exclude others – us/them collaborations. (shrink)