Carpometacarpal (CMC) arthritis of the thumb is one of the most common pathologies encountered in clinical hand and orthopedic surgery practices. Anatomy of the CMC joint and its biomechanics are theorized to predispose the articulation to laxity and subsequent degenerative changes. Diagnosis of CMC arthritis is primarily based on history, physical examination, and imaging findings, all of which coalesce to guide treatment. There are a multitude of treatment options for CMC arthritis, each with its own set of pearls and pitfalls with treatment decision making shared by surgeon and patient. Continued research and longitudinal data on outcome measures will assist in determining the ultimate "rule of thumb" for the treatment of CMC arthritis.