The problem of moral luck is there is a contradiction in our common sense idea of moral responsibility. We believe that a person can become more blameworthy as a matter of luck. Nevertheless, the idea that luck affects moral responsibility contradicts another feature of our thinking: A person's blameworthiness cannot be affected by that which is not within her control. This book defends the claim that luck in results, circumstance, and character can partially determine the degree of a person's blameworthiness. It provides a unique way to advance the debate about moral luck by appealing to arguments in metaphysics, epistemology, ethical theory, and moral psychology.