In this article, we formalise and investigate the following problem. A number of decisions must be delegated to a collection of agents; once the decisions are delegated, the agents to whom the decisions are delegated will then make these decisions rationally and independently, in pursuit of their own preferences. A principal is able to determine how decisions will be delegated, and seeks to do so in such a way that, when the decisions are ultimately made, some overall goal is satisfied. The principal delegation problem, is then, given such a setting, whether it is possible for the principal to delegate decisions in such a way that, if all the agents to whom decisions have been delegated then make their respective decisions rationally, the p...