Two very similar chemicals, psilocybin and psilocin, are the active psychedelic ingredients in many species of mushroom.* Upon seeing the common term “magic mushrooms,” or simply “shrooms,” readers may think of familiar references to the recreational use of the fungi, such as  the Jefferson Airplane song White Rabbit. The former Harvard psychology professor and LSD advocate Timothy Leary attributed his initial inspiration to psilocybin, and encouraged the use of such substances in an essentially uncontrolled manner. However, serious scientific study of psilocybin, abandoned for many years in the wake of the 1960s, has now begun again. Partly funded by the Multidisciplinary Association for Psychedelic Studies (MAPS), it suggests much more concrete benefits than some might think.