The lateral collateral ligament (LCL) of the elbow is a complex capsuloligamentous structure critical in stabilizing the ulnohumeral and radiocapitellar articulations. LCL injury can result in elbow instability, allowing the proximal radius and ulna to externally rotate away from the humerus as a supination stress is applied to the forearm. Elbow dislocation is the most common cause of LCL injury, followed by iatrogenic injury. LCL pathology resulting in late recurrent instability is rare but disabling. The diagnosis requires a high index of suspicion, detailed history, and focused physical examination maneuvers. Stress radiographs are often the most useful imaging modality. Despite controversy over the anatomy of the LCL complex and the relative importance of its component structures, treatment of late instability is focused on lateral ligament reconstruction from the humerus to the ulna using tendon grafts with reasonably good outcomes.