There are three sets of defenses that might be used to avoid enforcement of a contract which is otherwise valid: (i) capacity related defenses; (ii) assent related defenses; and (iii) public policy related defenses. The topic of this podcast is the basic concepts related to the assent related defense of mistake. This podcast will also distinguish the doctrine of misunderstanding, which sometimes gets confused with mistake. Misunderstanding is not a defense at all, but a doctrine that when used prevents contract formation. At the conclusion of this podcast you should be able to (1) explain that a mistake is simply a belief that is not in accord with the facts; (2) identify and explain the two types of mistakes, unilateral mistakes by one party and mutual mistakes shared by both parties; (3) identify and explain when each will afford a defense to a contract; and (4) explain when a party might bear the risk of a mistake due to allocation of risk by contract, by “conscious ignorance,” or by other circumstances.