The present document's purpose is to do a conceptual approximation to outsourcing viewed from an Economic Agency Theory standpoint, determining structural and functional elements in order to perform an analytical process about its rise and current BPO (Business Process Outsourcing). A first description of Outsourcing's constitutive elements is carried out from different perspectives and authors researched via literature review and state of the art of this concept. Afterwards a description about the main postulates of Agency theory is performed, delimitating the orientation by which outsourcing will be analyzed and finally the pertinent conceptual link is done.