Introduces the field of psychedelic medicine. Explores the history of psychedelic use, from ancient practices to prohibition to modern clinical research. Topics include pharmacology and neurobiology of prototype compounds─i.e., classic psychedelics (psilocybin, LSD, DMT), empathogens (MDMA), and dissociatives (ketamine). Covers brain imaging studies addressing effects on brain function, connectivity, and plasticity. Analyzes growing clinical research investigating psychedelic therapeutics for depression, post-traumatic stress disorder, anxiety disorders, and substance use disorders. Addresses safety/efficacy, ethics, and the legal landscape, including U.S. Food and Drug Administration and Drug Enforcement Agency regulation and state-level reforms. Emphasizes critical thinking in assessing scientific studies, understanding nuances of psychedelic-assisted therapy, and appreciating societal implications of integrating these powerful compounds into medicine.