T.M. Scanlon's On What We Owe to Each Other is one of the most significant works in moral philosophy of recent years. It presents distinctive views on reasons, value, and well-being, and offers a contractualist account of moral wrongness and significance. It has initiated debates on the nature of value, the role of well-being, how numbers matter in deciding what we should do, and the role justifiability plays in our moral thinking. In On What We Owe to Each Other, five leading moral philosophers assess various aspects of Scanlon's moral theory as laid out in this seminal work.