Post-1966 Underground Period of Psychedelic Research

The Post-1966 Underground Period of Psychedelic Research was the passage of psychedelic therapy from public, institutionally sanctioned inquiry into a smaller and often illegal world of private guides and clandestine practice. It was not a clean break: practitioners carried forward methods and relationships formed during the first research wave, and their work later fed into university studies. The period therefore marks both a loss of formal scientific infrastructure and the survival of a therapeutic tradition beyond it.

The Collapse of the First Wave

The turn underground followed a rapid institutional retreat. In April 1966, Sandoz withdrew LSD-25 from circulation amid mounting controversy, transferring most of its remaining supply to the U.S. government. Many of the roughly seventy research programs then operating shut down. The decision narrowed access to the drug at the very moment that psychedelic therapy was already provoking professional unease: its high-dose sessions sought a transformative experience in one encounter, rather than the familiar pattern of continuing weekly treatment, and asked researchers to reconsider the roles of therapist and patient.

In May, the United States Senate held hearings on LSD. Timothy Leary and Sidney Cohen testified in defense of research and tried to distinguish clinical use from the growing black market. Senator Robert F. Kennedy questioned why projects considered worthwhile six months earlier should now be cancelled, and warned that banning medical use because of illicit use would deprive the country of a potentially helpful treatment. His intervention did not reverse the crackdown. By October, the Food and Drug Administration had ordered about sixty researchers across the country to stop their work.

The order arrived at a strikingly specific moment at the International Foundation for Advanced Study in Menlo Park. James Fadiman had just administered psychedelics to four people taking part in problem-solving experiments when the letter revoking the project’s approval arrived. He and his colleagues delayed acting on it until the next day; then the program, along with virtually every other American research effort still under way, closed. The episode makes the shutdown more than an abstract change in policy: a research network was interrupted in the middle of its work, while its participants were already undergoing the very experience it had set out to study.

A Narrow Institutional Exception

One substantial research program survived the 1966 closures. At the Maryland Psychiatric Research Center at Spring Grove, researchers including Stanislav Grof, Bill Richards, Richard Yensen, and Walter Pahnke continued studying psilocybin and LSD. Their work addressed alcoholism, schizophrenia, and the existential distress of cancer patients. The program persisted until 1976, a decade beyond the shutdown of most comparable American projects.

Why Spring Grove remained open is not certain. Some researchers whose programs had been closed speculated that the center served powerful people in Washington who valued the treatment or wanted continued access to the drugs. Former staff members interviewed about the center doubted that account. They instead pointed to director Albert Kurland’s strong standing with federal officials and his connections in Washington, which helped keep the program operating and secure LSD, including some supplied by the government. Spring Grove was an exception, not a restoration of the earlier research landscape: the broader work had moved out of public view.

Guides, Lineages, and Protocols

The underground described in this history is not simply the illegal market for making and selling drugs. It consists of a comparatively small group of guides and therapists who used psychedelics in prescribed settings, intending to treat illness or support spiritual, emotional, or creative development. Their backgrounds varied widely. Some were credentialed therapists or religious professionals; others drew on traditions associated with the human potential movement and alternative therapeutic practice. Because the work remained illegal, practitioners risked both their freedom and, where applicable, their professional licenses, and interviewees asked that their identities and locations be concealed.

Many of these guides traced their professional lineage to therapists active when psychedelic work was still legal, including Timothy Leary, Stanislav Grof, Al Hubbard, and Leo Zeff. Zeff, an Oakland Jungian therapist, became one of the best-known underground practitioners. After an LSD experience in 1961, he began using a range of psychedelics with patients, finding that they could bring unconscious material into awareness and produce spiritual insight in a single session. When the federal government placed psychedelics in Schedule I in 1970, he chose to continue his work underground despite the personal strain and risk.

Zeff helped turn that hidden practice into a more defined therapeutic discipline. He described agreements with clients that emphasized strict confidentiality, forbade sexual contact, and required obedience to the guide’s instructions during a session. He also valued ceremonial details, including giving the medicine in a cup, which he regarded as a symbol of transformation. His approach differed from conventional analytic detachment: he believed guides should have personal experience with the medicines they administered, should not steer a client’s journey toward a predetermined destination, and could offer personal warmth or comforting touch during a difficult session. These practices were neither simply a continuation of hospital treatment nor an abandonment of structure. They supplied a social and ceremonial framework for work that could no longer rely on public clinical institutions.

Knowledge Carried Across the Divide

The formal closure of research did not erase the earlier therapeutic experiments. In his introduction to The Secret Chief Revealed, Myron Stolaroff argued that the renewed legitimate research beginning in the late 1990s had developed partly from the anecdotal evidence accumulated by underground therapists such as Zeff, as well as from the first wave’s published and clinical work. The exchange between the underground and universities was limited and cautious, but not absent. Some experienced guides were recruited to train a new generation working in university trials; when Johns Hopkins University researchers studied music in guided psilocybin sessions, they consulted underground guides about their musical practices.

This continuity also explains why the period is better understood as a transfer of knowledge than as a simple disappearance. The first wave had already tested competing ways to frame psychedelic action: as a model of psychosis, as an aid to psychoanalysis, or as a potentially transformative experience. Underground guides preserved practical knowledge about preparation, the therapeutic setting, the guide’s conduct, and the experience that might follow. Their testimony was often anecdotal rather than produced under the standards of a modern clinical trial, but it offered a body of experience that later researchers could not recover from formal publications alone.

Return to the Clinic, Return of the Dispute

When university research resumed, the earlier tensions returned with it. Psychedelic trials are difficult to blind because participants and guides can often tell whether the participant received psilocybin or a placebo. Researchers also struggle to separate a drug’s effects from expectations, the session environment, and the presence of therapists. The treatment presents a further challenge to a strictly pharmacological model: its apparent value may depend on the experience it occasions, including experiences described as spiritual. Charles Grob called psychedelic therapy a form of applied mysticism, a formulation that exposes how far it crosses conventional divisions between medicine and religion, illness and health, and drug action and therapeutic context.

By December 2016, the New York University and Johns Hopkins University cancer studies had brought striking results back into public view. Across the two trials, about 80 percent of patients showed clinically significant reductions in anxiety and depression, maintained for at least six months; the intensity of reported mystical experience closely tracked the degree of symptom relief. The studies included only eighty subjects, so larger trials were still needed before rescheduling or approval could be considered. Even so, the findings drew support from the mental health establishment, medical schools sought to take part in future trials, and New York University gave the work greater institutional standing.

That renewed legitimacy did not settle what psychedelic therapy should become. At a later conference, former leaders of the mental health establishment praised the model of psychedelic-assisted psychotherapy but stressed the need for rigor, safety, and distance from recreational use. Bob Jesse, Rick Doblin, and Katherine MacLean also considered a broader future: Jesse favored trained guides working in enduring, multigenerational communities, while Doblin and MacLean differed over whether wider acceptance should mean legalization or more controlled access. The underground period thus left two inheritances. It helped keep therapeutic knowledge alive when institutions withdrew, and it preserved the question that the clinic’s return could not resolve: whether these experiences belong only to medicine, or also to a larger social and spiritual practice.