Freedom of belief is one of the entrenched values in modern society. Interpreted as the right not to be coerced into believing something, it is surely correct. But most people take it to mean that there is a right to false belief, a right to be wrong. People think that freedom of thought is a good thing, and this must include the freedom to make mistakes. It is also often thought that making mistakes is a life-enhancing and essential part of personal development. I argue that these ideas are false. Beginning with an examination of the basic good of truth, and making comparisons with other goods like health and friendship, I argue that there is a duty to believe only the truth, which thus logically excludes the right also to believe falsehood. I distinguish between the strict wrongness of false belief and the fact that, because of our epistemic limitations, we are not always to be blamed for our false beliefs. Even in the case of those beliefs which are involuntary, there is no right to have them if they are false, even though we are not to be blamed for having them. The right to be wrong, I conclude, is a modern myth.