Despite the increasing amount of literature on the legal and political questions raised by liberty of conscience, an explanation for the normative significance of conscience remains elusive. In our view, a compelling explanation of the normative significance of conscience is a much needed addition to the literature. In our paper, we attempt to show that the few attempts to explain the normative significance of conscience are faulty. However, we offer an alternative account grounded in contractualist moral theory that we believe effectively utilizes the resources of the contractualist tradition in moral philosophy to explain why conscience matters.