Significant contemporary advances have permitted a more comprehensive understanding and development of some interesting concepts about the glenohumeral joint. The purpose of this review paper was to discuss current concepts related to the anatomic stabilizing structures of the shoulder joint complex and their clinical relevance to shoulder instability. The clinical syndrome of shoulder instability represents a wide spectrum of symptoms and signs which may produce various levels of dysfunction, from subtle subluxations to gross joint instability. The glenohumeral joint attains functional stability through a delicate and intricate interaction between the passive and active stabilizing structures. The passive constraints include the bony geometry, glenoid labrum, and the glenohumeral joint capsuloligamentous structures. Conversely, the active constraints, also referred to as the active mechanisms, include the shoulder complex musculature, the proprioceptive system, and the musculoligamentous relationship. The interaction of the active and passive mechanisms which provide passive and active glenohumeral joint stability will be thoroughly discussed in this paper.