Multiple sclerosis (MS) is a devastating neurologic illness that affects 250000-350000 Americans and is second only to trauma as the leading cause of neurologic disability among young adults. The hundreds of case reports and many retrospective reviews on pediatric and adolescent MS provide clear evidence in the literature that it exists. MS will not be encountered often in primary pediatric practice. Only 2% of patients with MS have onset of their illness before age 21 years, but this article shows that it can be diagnosed with the proper index of suspicion. Early diagnosis is of particular importance because of the investigation of medications that have been proven to prevent the progression of illness and disability. Because of the advances in preventative therapies, the timely and accurate diagnosis of MS in childhood is of utmost importance to prevent future disability. This article presents a case of a preadolescent MS, reviews MS in detail, and highlights the literature to date on pediatric MS to provide clinicians with the knowledge to arrive at a speedy and accurate diagnosis.