Why do larger corporations have more layers in their hierarchy? My contention in this paper is that hierarchies arise because economic agents have limited ability to anticipate and ascertain every possible contingency they are faced with. As a result, the complete contract may become too complex (or too costly) to devise and manage directly. My contention in this paper is that hierarchies may help a limited-ability principal (the organization's president) collect all pertinent information about the productive elements in the organization so that the complete is again possible. The contributions of the paper are six-fold: 1) it suggests a reason why hierarchies exist; 2) it develops a measure of the quantity of information that needs to be processed at each level of the organization; 3) it measures endogenously the optimal number of layers in a hierarchy given the players' ability to process information; 4) it provides a rationale for having the most talented individuals at the top of the hierarchy; 5) it offers an explanation for the existence of an unique president in an organization; and 6) it explains how the number of layers and of managers may vary over time as the company grows and/or the players' ability changes.