This chapter provides a review of literature on key human resource management concepts used in empirical studies described throughout the book. The chapter commences with a description of several green human resource management practices, followed by the identification of specific practices employed in the Sri Lanka Air Force. The literature on high-performance work practices is reviewed as such practices that have been successful in achieving high levels of employee job performance. Leadership is also a predictor of employee engagement with descriptions of studies that relate leadership to innovation and job performance. Virtues are yet another predictor of employee engagement with loyalty and patience among the virtues that bind employees to the organization. Employee engagement is defined as consisting of cognitive employee engagement, emotional employee engagement, and behavioral employee engagement. Job performance is described as the ultimate goal of green activity.