Management of discoid lateral meniscus in a 6-month-old child is discussed. The patient presented with a lateral knee mass and an associated popping sound of the joint during flexion and extension. The diagnosis, which the authors believe to be the youngest presentation of this entity, was confirmed by arthrography. Computed tomographic features and magnetic resonance images of the discoid meniscus are presented. Management and theories of etiology of the discoid lateral meniscus are discussed.