This chapter addresses the treatment and rehabilitation of recurrent posterior instability of the glenohumeral joint with free bone block transfer. With the increasing recognition of posterior instability in military and athletic populations, this technique has shown promising outcomes, with failure rates below 14%. The chapter outlines potential pitfalls to avoid, such as suprascapular nerve injury and inadequate graft preparation, along with key surgical pearls including pre-operative planning using advanced imaging, meticulous dissection during arthroscopy, and careful placement of the bone block to enhance outcomes. By understanding the risks associated with failed repairs and incorporating advanced techniques, free bone block reconstruction emerges as a viable solution for addressing posterior instability.