Workers will not pay for general on-the-job training if contracts are not enforceable. Firms may if there are mobility frictions. Private information about worker productivities, however, prevents workers who quit receiving their marginal products elsewhere. Their new employers then receive...

"Implicit Contracts, incentive compatibility, and involuntary unemployment" (MacLeod and Malcomson, 1989) remains our most highly cited work. We briefly review the development of this paper and of our subsequent related work, and conclude with reflections on the future of relational contract...