Leary claimed that, in the right dose, setting, and guidance, psychedelics could alter behavior that benefits individuals more than regular therapy. A lot of his research was centered on reforming criminals and treating alcohol abuse. Most of his research subjects reported profound spiritual experiences that left a positive impact on their lives. According to Leary's autobiography Flashbacks, 300 professors, graduate students, writers, and philosophers had taken LSD, and 75% reported it as “one of the most educational and revealing experiences of their lives”.
The Concord Prison Experiment was conducted to analyze the effects of psilocybin combined with psychotherapy on rehabilitation of released prisoners after being guided through the psychedelic experiences. Generally, the average recidivism rate was 60% for American prisoners. After the project, the recidivism rate for the prisoners who participated went down to 20%. Thirty-six prisoners reported to have sworn to give up future criminal activity. Leary concluded that psilocybin-assisted psychotherapy effectively resulted in a reduction in criminal recidivism rates.