A questionnaire, administered to random samples of students on the Yale and Wesleyan campuses, revealed that one of every five students on each campus had used hallucinogenic drugs at least once in his lifetime. Marijuana was by far the most popular. There was no appreciable difference between the two campuses as to whether students had ever used it or, if so, when they first tried it, but the students from Wesleyan used it more heavily and more recently. Wesleyan students were more likely to have used lysergic acid diethylamide (LSD) at some point and showed some tendency to have used it more recently, but did not differ significantly as to total cumulative use or the time they first tried it. For all hallucinogens, all users reported experiencing pleasant effects much more frequently than unpleasant effects. A majority of all nonusers reported knowing someone who had used hallucinogens, and a sizeable minority reported having seriously considered trying it.