Believing that p, assuming that p, and imagining that p involve regarding p as true—or, as we shall call it, accepting p. What distinguishes belief from the other modes of acceptance? We claim that conceiving of an attitude as a belief, rather than an assumption or an instance of imagining, entails conceiving of it as an acceptance that is regulated for truth, while also applying to it the standard of being correct if and only if it is true. We argue that the second half of this claim, according to which the concept of belief includes a standard of correctness, is required to explain the fact that the deliberative question whether to believe that p is transparent to the question whether p. This argument raises various questions. Is there such a thing as deliberating whether to believe? Is the transparency of the deliberative question whether to believe that p the same as the transparency of the factual question whether I do believe that p? We will begin by answering these questions and then turn to a series of possible objections to our argument.