This article questions the evidence base for some commonly accepted assumptions among bioethicists about the prevalence of neuroenhancement among college students and the degree to which putative neuroenhancers in fact enhance cognitive functioning. We argue that the evidence on the prevalence of stimulant drug use does not support bioethicists’ claims that neuroenhancement use of these drugs is widespread; that the evidence that putatively enhancing pharmaceuticals are truly neuroenhancing is much weaker than often supposed; that bioethicists have underestimated the challenges in assessing the safety and efficacy of putative neuroenhancers; and that the assumption that neuroenhancement is a novel development has deflected attention from historical experiences with other putatively enhancing pharmaceutical drugs such as cocaine and the amphetamines.