We create an environment in which congestion forces agents to match inefficiently early. We then introduce one of two centralized clearinghouse mechanisms. One of these has been successfully used to halt this kind of unraveling in a number of labor markets, while the other has failed. When it is...

This essay examines how repugnance sometimes constrains what transactions and markets we see. When my colleagues and I have helped design markets and allocation procedures, we have often found that distaste for certain kinds of transactions is a real constraint, every bit as real as the...

The theoretical literature on exchange of indivisible goods finds natural application in organizing the exchange of live donor kidneys for transplant. However, in kidney exchange, there are constraints on the size of feasible exchanges. Initially, kidney exchanges are likely to be pairwise...