This chapter deals with the discussion on the functional anatomy of the shoulder joint. It is important to understand the functional anatomy of the shoulder before assessing or treating any shoulder problem. Shoulder joint (glenohumeral joint) is the third largest joint in the body and is the most mobile joint in the body. It is a “ball and socket” type of joint with a large ball (humeral head) and a small, shallow, pear-shaped socket (glenoid). This mismatch allows an impressive degree of mobility in the joint. Static and dynamic stabilizers help to achieve stability. The osseous anatomy of the joint contributes little to static stability and majority of the stability is provided by the soft tissues around the joint. A brief discussion on static stabilizers which includes osseous anatomy of glenohumeral joint, glenoid labrum, capsuloligamentous complex along with its variations and mechanism of maintaining stability have been provided in this chapter. The main dynamic stabilizers of the shoulder are the rotator cuff muscles. The rotator cuff helps to center the head and provide compression force in all ranges of shoulder motion. Scapulothoracic mechanism, scapulothoracic movement, acromioclavicular (AC) joint, coracoacromial arch, glenohumeral movement on arm elevation and sternoclavicular (SC) joint are also covered in detail.