The 75-year history of marginality theory is reviewed and evaluated, leading to the recommendation that the use of the marginality idea be discarded by social scientists because it lacks construct validity. A review of the literature reveals that, at present, the concept of marginality is employed in five different social science lines of investigation. These models are examined fromthe perspective of their contribution to the validity of the construct and are found wanting. Marginality is shown to be a concept that did not fulfill its promise of explaining the effects on people of immigration, culture clash, and other transitional situations, such as status, role, or class changes. Evidence is presented that marginality is unscientifically founded and has been applied so indiscriminately as to be useless in the social sciences.