Inspired to help: for as long as he can remember, Eddie Marquis wanted to make a difference. So he joined the Peace Corps and stepped back into the closet.

Other young gay boys dream of growing up to be first mate, firefighter, or Olympic gymnast. Lifelong do-gooder and child of the 1960s Eddie Marquis fantasized about the Peace Corps. "I guess it sounds a little odd," laughs the Boston native, "but it's something I really wanted to do ever since I was a kid. It sounded so exciting."

Established by John F. Kennedy in 1961 to "promote world peace and friendship" through a variety of assistance projects, the Peace Corps has sent over 187,000 American volunteers to 139 countries in the past 46 years. The average age of a Peace Corps worker in 2007 is 28.

Marquis didn't exactly fit the profile. When he started seriously looking into joining the Peace Corps, he was 31. He needed a college degree--a prerequisite for service in the corps--which he received four years later, in human services advocacy, from the University of Massachusetts in Boston. He was in recovery, meaning he needed to be placed somewhere in the world with close access to a meeting in case he should need it. And he was openly gay.

Marquis's initial fear that the Peace Corps might discriminate against him in "don't ask, don't tell" military fashion turned out to be unfounded. The first Peace Corps recruiter he spoke with was an out lesbian who had served in Africa. Marquis recalls her saying, "So you're gay--so what?"

Once accepted into the Peace Corps, Marquis jokes, he started to make more requests. With his previous work at the AIDS Action Committee and other AIDS education centers in Boston, he wanted to work in HIV education and prevention. That last request would turn out to be easy to accommodate. Amanda Host, the Peace Corps press director in Washington, D.C., says that over 97% of the corps' posts worldwide have some aspect that is related to HIV or AIDS.

But while the Peace Corps back home was accepting of Marqnis's sexual orientation, it would be a different story in Ecuador. Before leaving for the South American country, Marquis received an information packet that advised gay and lesbian volunteers--for their own safety--to stay in the closet.

In July 2000 at age 38, Marquis went to a small, impoverished barrio in the provincial city of Santo Doimngo de los Colorados as a public-health volunteer specializing in HIV education. Arriving in Ecuador, Marquis immediately sensed why he had been urged to stay quiet about his sexuality.

"Being a gay man who has been out for a hundred years, it was the hardest thing," says Marquis, who had come out when he was 21. "It was such a homophobic place." Gay slurs, including the Spanish version of the f word, maricon, were frequently tossed around. Both of his host families, whom he otherwise enjoyed, told homophobic jokes and stories. Even educated locals had some fairly biased notions about gays.

A doctor he worked with and even considered coming out to told a classroom of students that homosexuals could turn people gay by looking into their eyes a certain way. When Marquis wouldn't agree with her in front of the kids, she got angry and told the class that they would take up the topic the following week when they discussed bestiality. "When she lumped homosexuality and bestiality together," says Marquis, "I pretty much knew that I wasn't going to be coming out to her."

Over the next 2 1/2 years Marquis went back into the closet--sort of. He wasn't open about his sexuality, of course. His partner was back in the United States, and they would visit each other every six months. "It was quite an adjustment," laughs Marquis. "I was frustrated quite a bit." But he managed to start an LGBT support group for Peace Corps volunteers in Quito. The first year only Marquis and his straight friends showed up, but by the second year other gay volunteers began to come.

Marquis loved his work educating the locals about HIV and AIDS and also teaching women's groups and nutrition classes. Three days a week he would play "nutrition bingo" with the women and children; they'd cook and talk about nutrition too. He taught about HIV and how to prevent its transmission but did not mention gay sex. Ultimately, Marquis acknowledges that, considering the machismo embedded in much of South America, coming out would have undermined his position as an authority on education. "I was a superstar down there," he says. "I was like Madonna; everyone wanted a piece of me because I was the gringo with the reliable information from the United States."

It's been 4 1/2 years since Marquis returned to the States, but not a day goes by that he doesn't think about Santo Domingo de los Colorados and what he did there. But with one dream fulfilled, Marquis is on to the next: Now 44, he's back in school to study nursing so he can join Doctors Without Borders. It's a way to "continue to do my part to help the planet," he says. "But maybe I'll make a little money this time."

Runnette is a freelance writer living in Los Angeles. He writes frequently for The New York Times.