Acromioclavicular joint dislocations are common injuries, particularly among young males who engage in contact sports. This chapter provides a comprehensive overview of ACJ dislocation, encompassing anatomy, biomechanics, injury mechanisms, classification systems, diagnostic techniques, and treatment strategies. Anatomically, the joint’s stability depends on both static (acromioclavicular and coracoclavicular ligaments) and dynamic (muscular and fascial) structures. Various classification methods—including Rockwood, Bannister, and the Circles method—guide management, although diagnostic accuracy remains a challenge. Treatment options range from physiotherapy to surgical stabilization, with controversy surrounding grade III injuries. Surgical strategies are tailored by timing (acute vs. chronic) and severity, utilizing suspensory devices, synthetic ligaments, or tendon grafts, often complemented by reconstruction of the acromioclavicular ligaments to restore horizontal and rotational stability. The chapter also discusses outcomes, post-operative rehabilitation, and management of equivalent or iatrogenic injuries. While no universal treatment algorithm exists, recent advances in classification and biomechanically informed reconstruction techniques continue to refine outcomes for this challenging and varied pathology.