Despite outsourcing has been at the core of managerial practice and literature for a long time, still authors do not agree on a clear understanding of the overall outsourcing process. This article answers two main questions, relevant to researchers and practitioners: 1.What are the main findings so far in outsourcing literature? 2. What do we still need to learn? Through a comprehensive review of the literature, we offer systematization of the existent body of knowledge on outsourcing, its implications on firms’ boundaries, and the theoretical challenges. In conclusion, implications for managers are drawn