This book develops a liberal theory of justice in exchange. It identifies the conditions that market exchanges need to fulfill to be just. It also addresses head-on a consequentialist challenge to existing theories of exchange, namely that, in light of new harms faced at the global level, we need to consider the combined consequences of millions of market exchanges to reach a final judgment about whether some individual exchange is just. The author argues that, even if we accept this challenge, the effect of it is minimal. For different reasons, normatively problematic collective market outcomes like externalities, monopolies, violations of the Lockean proviso, inequality, and commodification do not pose particular problems to the justice of market exchanges. He outlines the various conditions a market exchange needs to fulfill to be considered just from a liberal background and in light of the new harms. Ultimately, he shows, it is not the market which is to blame; if we want to tackle issues like global warming or global economic injustice, we should not blindly follow the intuition that we best restrain and regulate markets. Commutative Justice is unique in its focus on justice in exchange rather than on end-state distributive justice, and the way in which it addresses the new harms we are facing today. It will be of interest to researchers and advanced students in philosophy, politics, and economics who are working on questions of economic justice.