Although there is a strong relation between procurement and outsourcing, there is an unclear use of terminology in the literature. The purpose is therefore to unravel the interface between outsourcing and procurement and clarify how these two concepts relate to each other. The discussion suggests that outsourcing in much of the literature includes more than the definition of outsourcing allows. Leaning against accepted definitions of outsourcing and procurement, we present a description of the interface between these two concepts, thereby clarifying in what sense they overlap, and in which parts the two differ from each other.