Individuals given marijuana in experimental settings perform worse on tasks measuring attention, learning, and psychomotor skills related to performance in many jobs. Acute marijuana intoxication reduces performance in driving simulation, but effects are not consistent in actual driving situations. A significant positive relationship has been observed between some measures of self-reported marijuana use and wages among young adult men, while a significant negative relationship has been noted between some measures of self-reported marijuana use and labor force participation among young adult men. Individuals who test positive for marijuana in pre-employment drug screens are more likely to experience turnover, and employees who use marijuana are more likely to experience accidents. Although objective measures show no consistent relationship between marijuana use and work motivation, perceptions of the effects of marijuana use on motivation vary widely in different cultures. The author suggests hypotheses for future research addressing possible reasons for inconsistencies in past findings. 123 references and 2 tables