Personnel economics is the application of economic and mathematical approaches to traditional topics in the study of human resource management. This includes topics such as compensation, turnover, and incentives that are inherently economic, as well as those that do not at first appear to be economic topics (such as norms, teamwork, worker empowerment, and peer relationships.) Using the tools from advances in game theory, information economics, econometrics, and other areas of economics, personnel economics has come a long way over the last few decades. It now produces a large share of the labor economics literature, has earned its own code in the Journal of Economic Literature classification system (M5), and has its own working group within the National Bureau of Economic Research. In this paper, we review how this literature has developed and discuss some avenues for fruitful future research.