The findings show that adolescents who envisioned marijuana as making them feel relaxed, happy, and funny were more likely to have used marijuana; whereas, adolescents who had never used marijuana tended to view it as having negative physiological effects, such as feeling addicted, unhealthy, and depleted of energy. These findings suggest that marijuana users focus on its more immediate effects, and nonusers focus on the more distant long-term effects of regular use. Users' actual experiences with marijuana's effects influenced their expectations for its use; whereas, nonusers tended to focus on information on its effects they had received from drug education programs, which they perceived as more objective and authoritative than testimony from users themselves. Educational approaches that have focused on the negative effects of marijuana use have not been effective in reducing consumption by current adolescent users, however. This may be because adolescent behavior is characterized by experimentation and experiencing immediate pleasurable sensations, rather than harm avoidance and the management of current behavior according to long-term outcomes. The MEICA was developed from a survey of 142 children and adolescents (11-18 years old) between 2003 and 2005 in the southeastern United States. The MEICA was tested with a different sample of 144 adolescents 14 to 19 years old, and memory modeling was used to compare marijuana expectations of users compared with nonusers. 4 tables, 2 figures, and 41 references