Although Multiple Sclerosis (MS) occurring in childhood and adolescence has received increasing attention in recent years, the impact of the disease on cognitive function in this subgroup remains poorly understood. It has been posited that children and adolescents with MS may be particularly susceptible to cognitive dysfunction because the pathological processes, including inflammation, blood brain barrier breakdown, and demyelination, occur concurrently with ongoing myelination. Early work has documented that a number of these children present with cognitive deficits. However, there is no available information on the progression of these deficits, or on what clinical factors may predict further decline. The current article reviews what is currently known about pediatric MS and follows a cohort of pediatric MS patients and assesses cognitive function longitudinally. Participants were evaluated with a brief neuropsychological test battery on two separate occasions and correlational analyses assessed the relations between changes in cognition and several clinical variables including level of neurologic impairment, number of relapses prior to baseline assessment, number of interim relapses, age of disease onset, and disease length. The results indicate that a number of these patients experience further cognitive decline over time, or decline from previously normal functioning. Baseline level of neurologic disability was significantly correlated with changes in cognition. The number of interim relapses (i.e., relapses occurring between baseline assessment and re-evaluation) showed a modest relationship to changes in cognitive function, but this did not reach statistical significance.