ACT_UP was the acronym for the "AIDS Coalition to Unleash Power". This organization, both locally and nationally, created and defined AIDS activism and made it work. Its in-your-face protests and demonstrations were instrumental in waking up the mainstream community (as well as the more laid back memebrs of the LGBT community) that HIV infection and AIDS was both a looming health-care crisis, and one that would soon infect the mainstream community.

In its initial years, AIDS infections were seen almost exclusively among the more promiscuous members of the gay community, and AIDS thus came to be widely referred to as the "gay plague". As such, many of the "straight" community ignored it, with words such as "they asked for it" or "serves them right". Even many in the gay and lesbian community wanted to distance themselves from the stigma attached to AIDS.

But a more vocal minority, primarily in the gay community, were not ready to accept that branding, and also saw a looming health care crisis that would certainly soon also be indicated in the mainstream or "straight" community. These people saw little or no willingness in current government officials to do much more than pay lip service to AIDS, and a complacency among the media and the general population. They concluded the only solution to this problem, and the only way to release more funds to fight the disease, was to begin a campaign of radical actions and demonstrations to draw attention to the crisis.

Both Milwaukee and Madison established local chapters of ACT-UP, and held numerous public demonstrations that garnered attention and woke up the local communities and the state. They also participated in many national demonstrations. Nationally, ACT-UP was instrumental in waking up the Federal Government and getting then-President Ronald Reagan to back his Surgeon General and the Centers for Disease Control in their desire to apply more federal funding for research and prevention. It also successfully pressured the Food & Drug Administration to make early AIDS-fighting medications available faster, by considerably speeding up the approval process of new drugs that showed promise for critical illnesses.

Key members of the local chapter included activists Christopher Fons, Arnie Malmon, and many others.

The UWM Archives LGBT Collection holds a considerable amount of ACT UP Milwaukee's chapter papers. UWM Archives has this description of ACT UP in their collection description:

ACT UP (AIDS Coalition to Unleash Power) formed in New York in March 1987, following a speech by activist Larry Kramer calling for civil rights style demonstrations to protest the lack of government activity on AIDS. During the late 1980s and early 1990s, ACT UP New York staged many successful actions and chapters sprang up across the United States and Europe. ACT UP forced the government to shorten the drug testing and approval process; increase funding for AIDS research, care, and education; and promoted legislation to protect the right of HIV+ individuals. It was best known for a radical activist style that had not been seen since the 1970s. Tactics included non-violent direct action such as sit-ins, lock-downs, and road blockades. The group was especially known for its eye-catching graphics and memorable slogans (e.g., SILENCE=DEATH).

ACT UP Milwaukee's organizing meeting took place on August 18-19, 1989, when it hosted ACT UP New York and prepared for its first action. On August 25, the group demonstrated in front of the Federal Building to protest the federal and state governments' inadequate response to the AIDS epidemic. ACT UP Milwaukee described itself as "a diverse group of individuals united in anger and compassion and committed to direct action to end the AIDS crisis."

Many of ACT UP Milwaukee's actions focused on protecting the rights of HIV+ individuals, such as Dennis Hill. In 1991, Hill was arrested on a traffic violation and spent forty-eight hours in the Racine County jail. At the time, he was suffering from the advanced stages of AIDS. Milwaukee AIDS Project (MAP) staff found Hill in a cell, lying in his own feces and vomit. He died several days later. ACT UP Milwaukee staged many protests and letter writing campaigns around the issue of Hill's treatment by Racine County police. In 1990, ACT UP Milwaukee surveyed 200 area dentists to determine if they would accept HIV+ patients. About a third said they would not. In response, the group worked with the Wisconsin Dental Association and the Marquette University School of Dentistry to improve access to dental services.

During its short existence, ACT UP Milwaukee organized around numerous other issues, including the Marlboro/Miller boycott in 1991 (the parent corporation, Philip Morris Companies, Inc. was a major contributor to Senator Jessie Helms political campaign), the Cryptosporidium outbreak in 1993 that resulted in the deaths of several HIV+ individuals, and increased funding for AIDS services and education.

During its heyday, the organization had about 25 active members. By the mid-1990s, ACT UP Milwaukee--like most ACT UP chapters across the United States and Europe--was defunct.