While antitrust authorities strive to detect, prosecute, and thereby deter collusive conduct, entities harmed by that conduct are also advised to pursue their own strategies to deter collusion. The implications of such delegation of deterrence have largely been ignored, however. In a procurement context, we find that buyers may prefer to accommodate rather than deter collusion among their suppliers. We also show that a multi-market buyer, such as a centralized procurement authority, may optimally deter collusion when multiple independent buyers would not, consistent with the view that “large” buyers are less susceptible to collusion.