Chapter 22. Labor Markets and Referrals The use of social networks and personal referrals in the labor market is very widespread. Both firms and workers may find it beneficial to use these informal channels to produce successful matches between job seekers and vacancies. This Chapter discusses the existing literature and highlights the most robust results. It describes the theoretical literature on the use of informal search methods both in a micro and in a macro setting as well as the empirical findings in this area. The empirical evidence comes both from direct surveys of workers and firms and from indirect estimates that exploit structural modeling as well as natural experiments. Finally the Chapter discusses open questions and possible avenues for future research.