Closure of the rotator cuff interval is an important component of open stabilization techniques in shoulder surgery. This study describes a technique in which the deep layer of the capsule within the rotator cuff interval is closed arthroscopically. The effect of closure of this capsule within the rotator cuff interval on glenohumeral motion also is quantified. Sutures were placed from the superior glenohumeral ligament to the middle glenohumeral ligament and tied intra-articularly in fresh-frozen cadaveric shoulders. Closure of the interval capsule resulted in statistically significant limitation of humeral elevation, external rotation, and extension. Arthroscopic closure of the deep layer of the rotator cuff interval capsule produced a visible superior shifting of the middle and inferior glenohumeral ligaments and imbricated the anterosuperior capsule of the shoulder. In addition, this procedure can be performed in conjunction with arthroscopic capsulolabral reconstruction.