Chapter 4 introduces cognitive labor economics. Inspired by the industrial revolution, standard production functions model the transformation of physical factors of production into physical outputs. With the growing importance of higher level decision-making skills, we need to model inputs as cognitive and outputs as improvements in decision quality. The chapter discusses how to amend human capital theory to capture the open-ended tasks that are increasingly important to earnings. The chapter also introduces recent research measuring and modeling economic decision-making skills based on the ability to apply the principle of comparative advantage. It introduces evidence that these skills help explain earnings from employment, and outlines ongoing research to track these effects in the Danish population registries.