This paper, prepared for the Handbook of Game Theory, volume 4 (Peyton Young and Shmuel Zamir, editors, Elsevier Press), surveys work on reputations in repeated games of incomplete information. * We have benefited from our collaboration and discussions with many coauthors and colleagues over the course of many years, and we are deeply grateful to them. We thank Martin Cripps, Olivier Gossner and Yuichi Yamamoto for comments. We thank the National Science Foundation (SES-0961540 and SES-1153893) for financial support. Mailath thanks the Stockholm and Toulouse Schools of Economics for the opportunity to teach some of this material.