This chapter reviews the presentation of children with optic neuritis (ON) and compares these children to the 457 adults enrolled across the 15 institutions who participated in the ON treatment trial (ONTT). ON is part of a broader category of disorders, collectively referred to as the optic neuropathies, causing dysfunction of the optic nerve. Acute demyelinating ON may occur as a clinically isolated syndrome as in adults, or it may be concurrent with widespread demyelination as in acute disseminated encephalomyelitis. Visual recovery is usually good in children with ON. The ONTT has a tremendous impact on the use of multiple sclerosis (MS) therapies in adults with ON and other clinically isolated syndromes. Treatment is based on adult studies and includes short-term and long-term therapies, which may hasten some aspects of visual recovery and decrease the disease burden and risk of MS, respectively.