[5]: 6–7 Through the early months and spring of 1985, Petrelis suffered from a persistent illness that one doctor diagnosed as influenza; by that summer, he had developed a "bump" on his arm and was referred to a dermatologist at New York University (NYU) Hospital.

[32] In the aftermath of the Stonewall riots, he co-founded the Gay Activist Alliance (GAA),[1]: 50  where he was credited with developing the zap,[33] a protest tactic that would become a central component of ACT UP's strategy.

[34][35] Frustrated with what Bahlman called the "timid sort of nature" of GLAAD's and CLGR's tactics in the face of the AIDS crisis, Robinson and Noro determined that they needed to start a new group.

[40] Petrelis recalled, during this time, attending a community meeting at St. Vincent's Hospital at which he, alone, confronted Koch advisor John LoCicero and Carol Greitzer, Councilwoman from New York City's Third District where the River Hotel was located.

"[5]: 13–14 Petrelis also helped organize a Lavender Hill Mob demonstration, camping overnight in a tent outside Gracie Mansion, to protest the city's year-long delay in approving the contract and signing the paperwork for the River Hotel project.

[5]: 14 On February 24, 1987, Petrelis traveled with Bill Bahlman, Eric Perez, Marty Robinson, and Henry Yaeger[36]: 56  to Atlanta, Georgia, where the Centers for Disease Control (CDC) had convened the largest meeting yet held on the subject of AIDS.

Eight hundred state and federal health officials attended the two-day conference to discuss proposed CDC guidelines for the use of AIDS antibody testing in preventing the spread of the disease; specifically, the CDC was considering whether to recommend such testing of patients admitted to hospitals, patients seeking clinical treatment for family planning, drug addiction or sexually transmitted diseases, prison inmates, and couples planning to marry.

"[5]: 22 [42] Lavender Hill Mob members interrupted CDC deputy director Walter Dowdles' concluding remarks on the second day of the meeting, forcing the final plenary session to an early end with a "noisy demonstration accusing federal health officials of Nazism and genocide for debating the use of the AIDS test while people are dying for lack of a cure.

Having read the news of the Lavender Hill Mob's actions at the CDC, Kramer wanted to discuss such confrontational tactics as ringing the White House with protesters, disrupting congress, and shutting down Wall Street.

Kramer told Petrelis he was giving a speech at the Lesbian, Gay, Bisexual & Transgender Community Center on the upcoming Tuesday night, as a last-minute substitute for the scheduled speaker, writer Nora Ephron.

[5]: 23 On March 10, 1987, Petrelis was among approximately seventy-five people at the community center when Kramer gave the speech that marked the foundation of the AIDS Coalition to Unleash Power (ACT UP).

'[1]: 554 When ACT UP staged its first demonstration two weeks later, two hundred and fifty people descended on Wall Street to protest the relationship between the Food and Drug Administration (FDA) and Burroughs Wellcome, the maker of AZT, charging the pharmaceutical manufacturer with profiteering.

[62] With ACT UP/DC, Petrelis protested censorship of homoeroticism in the arts,[63] pressured Amnesty International to recognize people imprisoned for sodomy to be counted as victims of human rights abuse,[64] demanded an end to the United States' immigration restrictions against people with HIV,[65] traveled to President George H. W. Bush's family compound in Kennebunkport, Maine, to disrupt the president's vacation,[66] disrupted the National Conference of Catholic Bishops' press conference to protest Catholic Church's teachings on condom use,[67] helped stuff condoms and AIDS awareness posters into hundreds of vending box copies of The Washington Post to criticize the newspaper's AIDS coverage,[68][69] helped organize large demonstrations at the United States Capitol,[70] and launched a nationwide boycott of the Philip Morris Co. (now Altria Group, Inc.), to protest the company's support for Jesse Helms, a Republican senator from North Carolina.

[61] On April 20, 1990, Petrelis and other members of ACT UP/DC met with executives of the Philip Morris Co., makers of Marlboro cigarettes, to discuss the company's support for Jesse Helms, a Republican Senator from North Carolina.

Citing the length of time that had passed and the fact that the ACT UP chapters named in the complaint no longer existed, FEC general council Larry Noble eventually recommended the commissioners drop the case.

[86] On May 26, 1990, Petrelis held a press conference with Carl Goodman on the west steps of the United States Capitol to read the names of eleven officials, including eight members of congress and one entertainment executive who, the activists claimed, were secretly homosexual.

[14][15][16][17][18] Petrelis would later recall he had been "emboldened" to organize the press conference by an article in the San Francisco Examiner which attributed the prediction of a "national outing day" to writer Arthur Evans.

[101] Over the coming months, Petrelis led a small group of activists around the country, following the candidates to key primary states and successfully inserting the project's issues into the national debate.

[61] The project distributed condoms at campaign venues and offices,[98][102] produced a thirty-second television ad, accusing the candidates of ignoring AIDS, that sparked controversy when WMUR-TV in Manchester, New Hampshire, refused to air it because the station objected to the images of same-sex couples kissing,[103][104][105] challenged presidential hopeful Ross Perot's promise that his administration would not appoint homosexuals to cabinet posts,[106][107] and encouraged lesbian and gay voters to be skeptical about then-candidate Bill Clinton.

"[61] On December 17, 1992, Petrelis noticed a short item in The Washington Times about the October 27, 1992, beating death, in Sasebo, Japan, of Allen R. Schindler, Jr., a United States Navy seaman stationed aboard the USS Belleau Wood (LHA-3), who the newspaper said may have been gay.

[125] "The brutal death of Allen Schindler for daring to live authentically as a gay member of the U.S. Navy before the ban on LGBT people was lifted, at the hands of Terry Helvey, who pleaded guilty to the murder, demands that for justice to be served he remain incarcerated," Petrelis said in a statement.

[127] There, he continued to speak out and take action on a wide range of issues: advocating rent control,[127] protesting internet censorship,[128] criticizing how the National Institutes of Health (NIH) conducted and publicized a study on the use of nonoxynol-9 among men who have sex with men,[129][130] questioning the role of heterosexuals as leaders of lesbian and gay organizations,[131] opposing the death penalty, even in cases of fatal hate crimes,[132][133][134] criticizing Willie Brown, Mayor of San Francisco, for using a pejorative, "pantywaists," to insult United Airlines' airplanes,[135] and supporting state-mandated name reporting for people with HIV.

[141] In 1997, Petrelis helped organize a campaign to reopen the bathhouses, after San Francisco Board of Supervisors member Tom Ammiano proposed an ordinance to license and regulate the city's sex clubs, thereby codifying previously voluntary guidelines.

[144] Mitchell Katz, director of SFDPH, strongly opposed the initiative before it even qualified for the ballot; the San Francisco Chronicle editorialized against it, citing "disturbing evidence of an upsurge in dangerous sex practices among some gays.

"[145][146] Petrelis responded by demanding that critics reveal the evidence they claimed, while citing statistics showing decreased incidence of both male rectal gonorrhea and new AIDS cases in San Francisco.

[158][159] The GAO published the requested report in March 2000, concluding that federal AIDS programs were administered well and were effective, portending the reauthorization of the Ryan White CARE ACT.

Mark Vermeulen, the attorney representing Petrelis and Pasquarelli, said the activists were abiding by the restraining orders, the matter was being handled by the civil courts, and that there was no need for criminal prosecution.

The activists also admitted making similar phone calls to Jeffrey Klausner, the public health official from whose office at SFDPH the syphilis statistics had originated and one of the complainants in the criminal proceedings.

[177] In February 2002, Judge Perker Meeks of the San Francisco County Superior Court said he found sufficient evidence that Petrelis and Pasquarelli had made threats intended to cause fear and ordered the activists to stand trial.

[182] Nearly a year and a half later, the activists pleaded no contest to misdemeanor charges of making threatening phone calls to public health officials and reporters at the San Francisco Chronicle.