Professional sports offers a unique opportunity for labor market research. There is no research setting other than sports where we know the name, face, and life history of every production worker and supervisor in the industry. Total compensation packages and performance statistics for each individual are widely available, and we have a complete data set of worker-employer matches over the career of each production worker and supervisor in the industry. These statistics are much more detailed and accurate than typical microdata samples such as the Census or the Current Population Survey. Moreover, professional sports leagues have experienced major changes in labor market rules and structure-like the advent of new leagues or rules about free agency-creating interesting natural experiments that offer opportunities for analysis.In this paper, I focus on four areas of research on sports labor markets. First, using data on the rise and fall of rival sports leagues and the granting of free agency rights in professional sports, economists have tested whether employer monopsony lowers worker pay. Second, sports salary and performance data, and the knowledge of the race of each player in a sport, allow us to estimate the extent of discrimination in a much more detailed way than is possible in other industries. Third, changes in rules about the draft and player movement allow us to examine the claim of the Coase theorem that with complete information but no transactions costs or wealth effects, the ownership of a resource has no impact on the allocation of resources; rather, changes in such laws will only affect the distribution of wealth (Posner and Parisi, 1997). Finally, because of the observability of contract provisions, supervisor quality and worker behavior, one can estimate the impacts of supervision and incentives on behavior.