Two basic tenets of the Walrasian model, behavior based on self-interested exogenous preferences and complete and costless contracting have recently come under critical scrutiny. First, social norms and psychological dispositions extending beyond the selfish motives of Homo economicus may have an important bearing on outcomes, even in competitive markets. Second, market outcomes depend on strategic interactions in which power in the political sense is exercised. It follows that economics must become more behavioral and more institutional. We can return to these themes of the classical tradition, now equipped with the more powerful mathematical tools developed over the past century.

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 costly for firms and workers to be mismatched compared with the costs of matching early, the experimental observations reproduce the field observations. Furthermore, the experiment permits us to observe the transition between a decentralized and a centralized market, both when the centralized market fails to control unraveling and when it succeeds, at a level of detail unavailable in field data.

This paper tests the labor market signaling hypothesis for the General Educational Development (GED) equivalency credential. Using a unique data set containing GED test scores and Social Security Administration (SSA) earnings data, we exploit variation in GED status generated by differential state GED passing standards to identify the signaling value of the GED, net of human capital effects. Our results indicate that the GED signal increases the earnings of young white dropouts by 10 to 19 percent. We find no statistically significant effects for minority dropouts.