The posterior cruciate ligament (PCL) has been a misunderstood ligament for a long time, underrepresented in research literature. Recent advances in the basic and applied sciences, however, have begun to identify the functional importance of this "crucial" ligament. What sports health care professionals need to know about this ligament has been expertly summarized in this special edition of the Journal of Sport Rehabilitation (JSR) 8(4). The issue begins with a discussion of the anatomy and biomechanics of the PCL followed by management strategies and outcome data concerning conservative and surgical management. Proprioception and neuromuscular concerns are addressed as well as current concepts for rehabilitation and functional training for the PCL-injured athlete.