The principal-agent model assumes a functional division of labour. Principals delegate functions to agents, as they anticipate that the agents will implement those functions in a more credible and/or efficient manner. This chapter shows that there are also instances of non-exclusive delegation in the EU. That is, member states have delegated foreign policy functions to the European External Action Service, but individual member states continue to also carry out this function themselves. Cases of non-exclusive delegation present a challenge to the principal-agent model. First, they question the functional rationale behind the delegation process. Second, they question whether the hierarchical relationship between the principal and agent still holds. Third, they question the existence and relevance of an information asymmetry.