Up to 70% of multiple sclerosis (MS) patients experience cognitive dysfunction during the course of their disease. The most often affected domains are attention, memory, and information processing speed. Sequelae of cognitive dysfunction include negative effects on activities of daily living, employment, and relationships. This article reviews cognitive dysfunction in MS and focuses specifically on assessment, imaging, and risk factors. A number of neuropsychological batteries have been developed specifically for assessing cognitive dysfunction in MS patients. Trade-offs in length, administrative support, and efficiency exist between the various batteries. Modern imaging techniques provide a clearer picture of MS-related damage to the central nervous system, which is the major cause of cognitive dysfunction. Additionally, candidate risk factors have been identified that may help predict which patients will develop cognitive dysfunction.