When Timothy Leary told a crowd of San Francisco hippies to “turn on, tune in, drop out,” he cemented the link between psychedelic drugs and the free-loving, draft-dodging counterculture. The acidheads of the 1960s got high recreationally, swallowing spiked sugar cubes or small squares of paper at Woodstock or Monterey Pop. Today, you could recreate those bygone days at Bonnaroo or Burning Man — or you could head to New York City, where a group of modern LSD enthusiasts comes together annually in an entirely different context.

Back in October, I attended the Horizons conference, an educational forum that “examines the role of psychedelics in science, healing, culture and spirituality,” according to its website. Now in its eighth year, the conference offers attendees the chance to hear leaders in the field discuss the latest developments in hallucinogens. Past speakers have included Ethan Nadelmann, the founder of the Drug Policy Alliance, and Alexander Shulgin, the chemist credited with popularizing MDMA.

Horizons drew its largest ever audience last year. For three days, in between lectures like “Leading My Family to Ecstasy” and “Realizing Transformations,” over 200 people lunched on catered falafel, exchanged business cards over beers and, in many cases, shared personal stories of illicit drug use.

Dispatches from this psychedelic underground were diverse. When I arrived at a Friday night social that kicked off the conference, my first conversation partner was a 60-year-old woman from Massachusetts. “I’ve started using MDMA,” she told me, requesting I withhold her name due to the illegal nature of her confession. “I’ve done three sessions already.”

With her white hair and all-black outfit, the woman looked ready to curate an art museum, not rave at the club. But she said MDMA, the party drug known in pop culture as ecstasy or molly, has changed her life. When I asked how, she just grinned. “It’s not all fit for print,” she said, but the smile and subsequent look in her eyes let me know that the ecstasy has made her life, for lack of a better word, ecstatic. She offered a more PG example, too: because MDMA allows her to feel emotions more deeply, the drug has inspired her creatively. Now, she has begun writing a novel in her spare time.

Other attendees also praised the benefits of psychedelic drug use. One young guy told me about the “grandfatherly presence” magic mushrooms have played in his life, guiding him through times of distress. An older gentleman in a black turtleneck, who called himself an “unrepentant hippie,” said he worked as a therapist; he became interested in psychedelic drugs again when he learned they could help his patients manage anxiety and other conditions. “There are a lot of therapists here,” he added, waving his hand toward three men at a nearby table deep in conversation.

Save for the occasional tie-dye T-shirt, no one at the conference called to mind that 1960s acidhead stereotype. I interviewed ordinary people: men and women, young and old, students and professionals. What brought them all to Horizons was their shared belief in a kind of psychedelic medicine: that LSD, MDMA and similar substances can be used as more than mere recreational drugs.

Enter the world of psychedelic therapy, where doctors encourage patients to work through anxiety, post-traumatic stress and a host of other conditions while under the influence of psychedelic drugs. The idea of rolling on your shrink’s couch might sound absurd, but as I learned at Horizons, a growing body of evidence has come to support the practice. Now, supporters say the next step is to take faith in these healing trips mainstream.

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The term psychedelic comes from the Greek: a combination of psyche (soul) and deloun (to manifest or make visible). Most psychedelics work by interacting with the same mechanism in the brain that produces pleasure, which means that they generally induce a sense of euphoria along with their trademark visual distortions.

For most of history, humans used naturally occurring psychedelics, like ayahuasca, a potent hallucinogenic brew native to South America, and ibogaine, a chemical found in certain African vines. But the eventual advent of laboratory science changed how people tripped. In 1943, a 37-year-old Swiss chemist named Albert Hofmann was working in a pharmaceutical lab when he decided to ingest a small dose of a compound he’d first synthesized a few years earlier. As he cycled home from work, the substance induced fantastical effects. “I was taken to another world, another place, another time,” Hofmann later wrote of the experience. “At times I perceived myself to be outside my body.”

Back in the lab the next day, Hofmann told his supervisors about his strange journey with the substance: lysergic acid diethylamide. His bosses were eager to explore its potential pharmaceutical uses. Within a few years, researchers had completed an array of animal trials and began testing the drug on human subjects at the University of Zurich.

Soon, LSD traveled to America, where researchers began to study its effects at Harvard, the University of Chicago and other top universities. “By the mid-1950s, researchers had experimented with LSD during therapy for various neuroses, depression, addiction, psychosomatic illness, and emotional and physical trauma,” writes the journalist Tom Shroder, who chronicles the history of psychedelic medicine in his new book Acid Test.

At one point, private clinics even emerged to provide LSD-enhanced therapy to famous names like Briton Hadden and Cary Grant. “The action of the chemical releases in the subconscious…so that you can see what transpires in the depth of your mind,” Grant wrote of the sessions in his autobiography. “I learned many things in the quiet of that small room.”

By the mid-1960s, however, the rise of recreational LSD use began to overshadow the previous years of medical research. Thanks to Timothy Leary and other icons of the counterculture, medical psychedelics now had a huge PR problem, as the public grew to associate them with burning draft cards and dancing naked in the mud.

So did the federal government. In 1970, then-President Nixon banned LSD under the Controlled Substances Act, placing acid on a category of substances known as schedule I. The Drug Enforcement Agency classifies schedule I drugs, which include heroin and methamphetamine as well as most psychedelics, as having “no currently accepted medical use”: five little words that have been dogma for nearly five decades.

The federal ban not only ended the practice of legal psychedelic therapy, but also effectively thwarted most future research. “There’s a lot of bureaucracy,” said Peter Addy, a psychologist who presented his research on salvia at Horizons. Barriers to entry include everything from gaining approval for studies to obtaining samples of particular drugs. Funding poses a major difficulty.

In the face of these challenges, a committed group of supporters emerged to keep psychedelic medicine alive post-1970. In Acid Test, Shroder tells the story of Rick Doblin, who founded an organization called the Multidisciplinary Association for Psychedelic studies in 1986. Then a wild-haired hippie, Doblin hoped that MAPS could promote and fund psychedelic research, but he realized he needed to sharpen his image to become the public ambassador of LSD and other drugs. Many professional haircuts (not to mention one graduate degree from Harvard’s Kennedy School) later, Doblin and his organization have raised over $20 million to fund psychedelic research around the globe.

As Shroder wrote in an email, “Doblin is definitely a unique character, but his transformation is symbolic and parallel to the transformation in image of psychedelics themselves.” Alongside MAPS, money and support from organizations like the Heffter Institute and the Beckley Foundation has laid the groundwork for a new generation of psychedelic research.

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Of these more contemporary researchers, the scientist most likely to carry on Hofmann’s pioneering legacy is another Swiss man. Peter Gasser, who just this year published the results of the first human LSD study in four decades, took to the stage on the second day of Horizons to discuss his historic research.

Speaking from a lectern flanked by stained glass windows, Gasser said he drew on the psychedelic research of the 1960s to inform his hypothesis that LSD could ease anxiety in patients with terminal illnesses. Of the dozen subjects he recruited, only one had previously taken the drug, so he met with each at least twice before their first trip to answer questions and assuage fears. “Giving safety and confidence,” he said, “is the most important thing.” During the trips themselves, nurses measured the blood pressure and heart rate of each participant. Afterward, attendants monitored each patient overnight.

Gasser conducted each therapy session with a partner, a female psychotherapist. First, the patient ingested the drug. Once the LSD took effect, they would lie down, listen to music and discuss their feelings — often the same kinds of topics they’d discuss in a normal therapy session — with the pair of guides. “All emotions are enhanced” during a psychedelic trip, according to Gasser, which allows patients to cut to the heart of the issues they’re facing. Each of his sessions lasted eight hours, the length of an average acid trip.

“It was a pilot study,” Gasser said from the stage. “You cannot do a big statistical evaluation with twelve patients, that’s clear.” Still, he believes his results point to the therapeutic potential of LSD: All of his patients reported positive experiences. “After twelve months, people basically said it would help them, they would do it again and they would recommend it to other people,” he said. His findings were published twice this year, first in the Journal of Nervous and Mental Disease and then in the Journal of Psychopharmacology.

Many other presenters at Horizons shared firsthand stories of psychedelic research. John Harrison, an addiction specialist, led a MAPS-sponsored study examining how to treat opiate dependence with psychedelics. During the conference, he recounted how ibogaine could ease withdrawal symptoms and reduce cravings for harder drugs. Katherine MacLean, who conducted research at Johns Hopkins, told the crowd about how she discovered psychedelics could encourage long-term personality change, reducing anxiety and increasing one’s affinity for new experiences.

Toward the end of the day, representatives from New York University’s Psilocybin Cancer Anxiety Study played a clip from a new documentary about their research, which examines how exposure to the active chemical in magic mushrooms can reduce anxiety in terminally ill patients. In the darkened conference venue, testimonials from study participants played on a oversized screen.

Afterward, during the question and answer session, a woman rose to mention that her mother had participated in the study. Before she sat down, she added: “She thinks she got cancer so she could have that experience.”

Comments like these underscore the seriousness with which supporters of psychedelic therapy view their cause. Generally, speakers at Horizons maintained psychedelics could allow anyone — regardless of his or her state of mind — to expand consciousness and work through problems in the process. But current research into these drugs, the kind conducted by people like Gasser and the NYU team, focuses on their ability to heal traumatized groups like veterans, addicts and the mentally ill.

These studies have increasingly captured the attention of the public. Throughout the past few years, psychedelic therapy has made headlines in The New York Times and The Guardian, popped up in TED talks and been the subject of documentaries on CNN. The unprecedented attendance level at this year’s Horizons also speaks to psychedelic medicine’s growing prominence.

“We’re at a really interesting time right now, the turn of the century,” said Brian Normand Viveiros, the founder of Psymposia, a series of conferences series to Horizons. “I feel like we’re kind of in the Zeitgeist for this movement now.”

Zeitgeist or not, getting the public to take psychedelic therapy seriously will take time. The ghost of Timothy Leary still haunts public perception of the drug.

This became clear to me during a presentation by Annie Lalla, a relationship coach known for her belief that families can improve their relationships by taking MDMA as a group (“One trip on MDMA is like ten years of therapy,” she said, her heels clicking across the stage). During the Q&A, young people asked Lalla how they could recreate her success: how much MDMA should they give their own relatives? Should a person under 18 try psychedelics?

Others had a more basic question. “My mother doesn’t find taking drugs an acceptable path to improvement,” one man stuttered; he wanted to know how to persuade her. “I have my dad here,” began another young woman, pointing to the man sitting beside her.

After Lalla responded to the daughter, her father stood up. “I don’t need an altered state to love my family,” he said. “When you come back down, you may not be as sharp as you think you are.”

The point stuck: research and results can only go so far. No matter how many journals articles Peter Gasser writes, no matter how much money MAPS can raise, a makeover will likely prove the key to bringing psychedelics to the masses.

“What we’re all saying is, we have to talk about it,” John Harrison, the addiction specialist, told the crowd on Sunday — the last thing said at the conference. “Come out of the closet, say what we’re doing. We’re doing it with intention and consciousness. It’s a good thing.”