Grof is known in particular for his early studies of LSD and its effects on the psyche—the field of psychedelic psychotherapy. He constructed a theoretical framework for pre- and perinatal psychology and transpersonal psychology in which LSD trips and other powerfully emotional experiences were mapped onto one's early fetal and neonatal experiences. Over time, this theory developed into an in-depth "cartography" of the deep human psyche. Following the legal suppression of LSD use in the late 1960s, Grof went on to discover that many of these states of mind could be explored without drugs and instead by using certain breathing techniques in a supportive environment. He continues this work today under the title "Holotropic Breathwork".
