Study subjects will receive either 200 or 20 mcg (micrograms) LSD during two day-long psychotherapy sessions scheduled two to four weeks apart. Subjects in this study will have a 66% of receiving the full dose of 200 mcg LSD, and they have a 33% chance of getting the active placebo dose of 20 mcg LSD. Neither the researchers nor the subject will know whether he got 200 or 20 mcg LSD. Upon participant agreement, all psychotherapy sessions will be recorded to audio and video.