Theories on the etiology and management of myositis ossificans vary greatly. In this article, possible causative factors and treatment options are reviewed. We present a successful treatment regimen for myositis ossificans of the brachialis muscle in a 15-year-old football player. The treatment program emphasizes using joint mobilization and eccentric strengthening early in rehabilitation. The patient regained full elbow range of motion after nine weeks of this rehabilitation program. Follow-up at nine months revealed nearly complete maturation of the heterotopic bone formation, full pain-free range of motion, normal strength, and a safe return to athletic competition.