In 1937, Blount described progressive tibial varus deformity observed in otherwise healthy children and adolescents. Although he called the condition “osteochondrosis deformans tibiae,” the disorder is most frequently referred to as Blount disease. Two distinct clinical and radiographic forms have been recognized: infantile and adolescent. A third form, which was called “juvenile” Blount disease by Thompson, is recognized by some authors and is intermediate in severity and age of onset. The etiology of Blount disease is unknown. If the condition remains unresolved, it can lead to progressive varus deformity, with or without associated deformities of the distal femur and/or tibia; leg length inequality; and significant articular distortion, leading to premature osteoarthritis of the knee. A strong, but not universal, association exists between Blount disease and childhood obesity, increasing the prevalence and making effective treatment of this condition a challenge. Infantile Blount disease may resolve, respond to nonsurgical treatment, or be relentlessly progressive, so the surgeon must be astute in recognizing the features of true infantile Blount disease to determine effective treatment options.