Among many other published works, Sullivan is most well-known for his book, Information for the Female-to-Male Crossdresser and Transsexual, which he first published in 1980, which has since been revised and updated twice. He is also known for his work We Both Laughed in Pleasure – a selection of his diary entries, published posthumously. Sullivan’s main goal was to further the understanding of transsexual men and to push for better research into FTM medical procedures. At this time, when a trans* person medically transitioned, it was thought that they did so to live as a heterosexual (Lybarger). Sullivan, being openly gay, challenged that by being in a relationship with a cisgender man for eleven years before leaving him to pursue medical transition (Milks).

Sullivan expertly used his own personal testimony to convince doctors and other medical professionals that not only should he receive medical intervention by nature of being a transsexual man, but that he should regardless of whom he loves. A series of four interviews he gave with Dr. Ira Pauly are available on the Internet Archive, where Sullivan discusses the arguments he’d heard from medical professionals and other activists on his transition. The video interviews can be accessed by clicking here. Sullivan appeared to be largely successful in spreading the idea that gender and sexuality have no correlation to one another (Rawson), though there was a significant challenge from the then-present psychology community, who believed that only heterosexual trans* people could exist.

Outside of the medical world, Sullivan was a prolific activist. In 1986 he began hosting quarterly F.T.M. get-togethers and wrote about the meetings in a newsletter called, very simply, FTM (Milks). Many copies of FTM are still available for free reading on the Digital Transgender Archive. The newsletter accepted all sorts of writing and media from trans men and masculine folk throughout the world. Articles ranged from poems about masculinity, rituals for gaining stronger manhood, ads for “Menace Man” t-shirts and silicone packers, to studies on medical transitioning, erotic articles and short stories, photos of surgery, and state-by-state resources for newsletter readers.

In June of 1986, Sullivan underwent bottom surgery. In early 1987, he was diagnosed with AIDS (Lybarger). In the time before his death, he published his book, as well as a biography on Jack Bee Garland – someone also assigned female at birth who lived as a man and published many pieces of writing, and is assumed by contemporary standards to have been a trans man. Sullivan is known to be the first publicly recognized trans man to live – and die – from AIDS-related complications. The now famous quote from this difficult point in his life: “They told me at the gender clinic that I could not live as a gay man… but it looks like I will die as one.” (Milks)

Sullivan passed away on March 2nd, 1991, in San Francisco at the age of thirty-nine. We Both Laughed in Pleasure would not be published until 2019. Sullivan has since been honored on the National LGBTQ Wall of Honor at the Stonewall National Monument in 2019 (Keehnen) and Sullivan’s work has received widespread recognition online and in in-person trans* circles.