Twenty years ago, a furious speech by the playwright and activist Larry Kramer at New York City’s lesbian and gay community center birthed a new activist organization, ACT UP–the AIDS Coalition to Unleash Power. Within a month, weekly planning meetings were attracting 200 people, a motley mix of gay men, lesbians, recovering addicts with AIDS and the newly diagnosed, a great many of them just in their 20s. Though barely noticed in the pages of this publication, ACT UP would revolutionize AIDS research and treatment, as well as inject new life into the gay movement and infuse the tactic of direct action with its own style of theatrical militancy.

At the time, six years and at least 30,000 American deaths into the epidemic, Ronald Reagan had yet to give a public address on AIDS. Not a single drug was available to treat HIV. Prevention efforts had been left to volunteers and struggling nonprofits. The right’s solution was epitomized by William F. Buckley’s modest proposal that gay men with HIV have their buttocks tattooed.

For its first action, in March 1987, ACT UP sent some 250 activists to descend on Wall Street. Armed with cardboard tombstones and anti-Reagan posters, they chanted, “Release those drugs,” lighting a fire under the Food and Drug Administration and drugmakers to speed up research and approval. Two years later pharma giant Burroughs Wellcome was finally marketing an HIV treatment but had priced it (AZT) at an impossible $8,000 a year. So ACT UP returned to Wall Street, but this time activists didn’t just picket. As former bond trader Peter Staley recalls, “We [had] sealed ourselves into one of their corporate offices using high-powered drills. They didn’t back down, so we upped the ante by shutting down the New York Stock Exchange, sneaking past security and using foghorns to drown out the opening bell. The company finally lowered the price three days later.”

During the years that followed, ACT UP stormed the National Institutes of Health, the FDA and the Centers for Disease Control to protest their shortcomings. On the local level, Catholic dioceses and boards of education were targeted for blocking HIV information in public schools; city governments for failing to provide care and housing; jails and prisons for setting up segregation units. Some ACT UPers set up guerrilla needle-exchange programs; others staked out the entrances to junior highs to distribute condoms directly to students. Just as essentially, ACT UP members became self-taught experts in such arcane fields as virology and patent law and in so doing rewrote the patient-doctor relationship and helped put the idea of universal healthcare–now favored by a majority of Americans–on the political map.

Along the way, ACT UP borrowed strategies from other radical movements: antinuke protesters for techniques on civil disobedience, antiapartheid campaigners for bringing political funerals to the streets. Many of its tactics–videotaping demonstrations as protection against police brutality, coordinated but autonomous affinity group actions–have become standard fare in the global justice movement, as has ACT UP’s deeply democratic tradition.

ACT UP is now a shadow of its former self, but its alums have gone on to found Health Gap, a driving force for global treatment access; the Treatment Action Group, which continues to push the AIDS research agenda; and Housing Works, which has won housing for thousands of New York City’s HIV-­positive homeless. And true to form, the organization will mark its twentieth anniversary with a march on Wall Street March 29 to demand single-payer healthcare for all.

Today, anyone who gains access to an experimental drug before it’s approved, or takes a life-saving medicine that was fast-tracked through the FDA–indeed, anyone engaged in the struggle for healthcare–is indebted to ACT UP’s audacity and vision.