This dissertation contains three chapters. Each applies the tools of applied microeconomics to questions in labor economics, the economics of education, and social economics, respectively. In the first chapter, which is joint work with Amanda Pallais, we present the results of a series of field experiments in an online labor market designed to test whether workers referred to a firm by existing employees perform differently from their non-referred counterparts and, if so, why. We find that referred workers have higher performance and lower turnover than non-referred workers. We demonstrate a large role for selection: referred workers perform better and persist longer even at jobs to which they are not referred at a firm where their referrers do not work. Team production is also important: referred workers are much more productive when working with their own referrer than with someone else's referrer.
