Abstract Instability of the long head of the biceps brachii tendon is a recognized source of shoulder pain. However, this diagnosis is usually associated with concomitant pathology including subscapularis tendon tears. The appropriate diagnosis of biceps incarceration or instability remains challenging, with failure to address instability being likely to result in persistent pain and disability despite arthroscopic management of concomitant shoulder pathology. The objective of this article is to (1) describe a dynamic test performed both preoperatively and intraoperatively, termed the “biceps incarceration maneuver,” to help identify biceps instability; (2) reinforce the concept that biceps instability must be ruled out in young patients presenting with anterior shoulder pain; and (3) report that with proper diagnosis and treatment, patients with biceps instability will experience rapid symptomatic resolution after management. Technique Video video See video under supplementary data.