Excuses are commonplace. They are part and parcel of our ordinary practice of holding each other morally responsible. But excuses are also curious. They have normative power. Whether someone has an excuse for something they have done matters for what it is rational to think and feel and do about their action. The considerations we appeal to when making excuses are a motley bunch: they range from tiredness, stress, various distractions (a looming work deadline, a wailing infant), poverty, duress, and ignorance of various kinds. My aim is to explain when and why these considerations function as excuses and what unifies them as a class. I am particularly interested in the question of just what exactly the normative power of excuses consists in and how far this normative power extends.