Acquisition of scientific information regarding the neuropsychological aspects of multiple sclerosis has been hampered by studies using small, inadequately described patient and control samples and a wide array of cognitive test procedures that hinder multicenter data pooling. Based on a review of key issues of clinical need and experimental interest, research guidelines are proposed for investigations in this burgeoning research area. The guidelines include suggestions for sampling methods, population characterization, and control groups as well as a recommended core battery of neuropsychological tests for use in this population. It is hoped that these guidelines will advance knowledge about the neuropsychology of multiple sclerosis by helping to promote sound experimental design, facilitate cross-study comparison, and encourage multicenter collaborative efforts.