How do we form and modify our beliefs about the world? While accepting that what we believe is determined by evidence, and therefore is not directly under our control, Professor Helm argues that no theory of knowledge is complete without standards for accepting and rejecting evidence as belief-worthy. These standards, or belief-policies, are not themselves determined by evidence, but determine what counts as credible evidence. Unlike single beliefs, Helm argues, belief-policies are directly subject to the will, and consequently to weakness of will and self-deception. Helm reveals the importance of the idea of belief-policies in several areas of philosophy, in particular the philosophy of religion.