Conservation of Resources (COR) Theory was originally developed by Stevan Hobfoll in the 1980s to explain human motivation (Hobfoll, 1988). Since then, it has been used in organisational behaviour research to explain stress and individual behaviour at work. More recently, it has been used in the human resource management (HRM) discipline, which will be the focus of this entry. The basic tenet underpinning COR Theory is that “individuals are motivated to protect their current resources and acquire new resources” while balancing the priority to conserve the resources that are most important to them (Halbesleben, Neveu, Paustian-Underdahl & Westman, 2014: 1335). This chapter will present an overview of COR theory and its developments, before presenting key areas for future research in human resource management.