If sound policy is to be made on the issue of marijuana in the workplace, all available empirical evidence about its impact on job performance should be utilized in the decision process. Although a substantial amount of relevant research has been done, the results published in journals in widely divergent fields, are not easily summarized and present no single, simple message for decision makers. Schwenk and Rhodes offer a unique review of this complex body of work and challenge the many highly publicized but scientifically unsound mythical numbers touted as supporting various policy...