Cognitive deficits in adult multiple sclerosis (MS) are well documented; however, little is known regarding cognitive impairments in similar childhood conditions. This study compared cognitive profiles of children aged 7-18 years with MS (N = 9) to those with acute disseminated encephalomyelitis (ADEM) (N = 9), a similar but monophasic condition. Individual profiles showed clinically relevant impairments across all cognitive domains evaluated. Differences in severity and spread were also found. Results suggest a gradient effect, with the transient white matter disruption in ADEM resulting in subtle cognitive impairments, while the multiple insults to white matter in childhood MS are associated with more severe sequelae.