Incorporating the decision of how to organize the acquisition, use, and communication of knowledge into economic models is essential to understand a wide variety of economic phenomena. We survey the literature that has used knowledge-based hierarchies to study issues such as the evolution of wage inequality, the growth and productivity of firms, economic development, and the gains from international trade, as well as offshoring and the formation of international production teams. We also review the nascent empirical literature that has, so far, confirmed the importance of organizational decisions and many of their more salient implications.