DaJuan Hawkins spent four months in jail for assault and thought he was destined for a life of street crime.
Today, the high school senior is heading for college and writing poetry.
What transformed Mr. Hawkins and Mr. Marchesi into confident, productive, and compassionate human beings, they say, is the Council for Unity.
Founded as a small antigang group in 1975, the council now claims to reach 100,000 people of all cultures in New York City, Milwaukee, and San Francisco, and as far away as Nigeria and the Republic of Moldova.
Its mission has also grown: The council recently published a book of student writings. It works with families and in correctional facilities. It is developing a public-safety curriculum in partnership with police in Riverhead, Long Island.
The group's story begins with its founder, Bob De Sena, a one-time gang member and former English teacher at the same Brooklyn school Marchesi attended.
Mr. De Sena says he turned his life around because someone gave him a second chance. He wants the Council for Unity to do the same for new generations of kids who have had rough lives.
The group has a 33-year history of getting gang members together to talk, believing that when everybody comes together, there's nobody left to fight.
At Christopher Columbus High School in the Bronx, a borough of New York, gang activity ceased after council classes were introduced, says principal Lisa Maffei-Fuentes. She says her school was on the city's most dangerous list three years ago.
"They've come to respect their home site, their school," she says.
Former gangsters drive the program, taught as a course in elementary, junior, and senior high schools and colleges and offered at community centers and prisons. They take the lead in finding solutions to conflicts without violence while learning communication and leadership skills.
The statistics are impressive given the group's small budget — $1.7 million a year, with support from the teachers union, the city, and its board of directors.
Sean "Dino" Johnson, who heads the council's school-based initiative, spent time behind bars for drug trafficking and weapons possession. He counseled prison youth at Sing-Sing, but "had no expectations of ever going home."
That changed in 2004 when he met De Sena.
"Bob told me, 'We need people like you on the outside,' " says Johnson, who was hired by De Sena when he was released. "No one ever told me that people like me were needed."
"When they see someone who's been to hell and back, it clicks: 'If he can do it, I can do it,' " Johnson says.
Before Hawkins joined the council, he said his life was a daily ritual of "fighting and winning." Through the council, he channels his leadership qualities to counsel other youth.
Hawkins was among some 20 high school students at the council's cramped office recently. Like Hawkins, most were former gang members who have done time. But on this day they spoke enthusiastically about their futures.
Hawkins told his story in a poem: "Before you I was a mess. Before you I couldn't care less.... Together forever I say this fluently, Together forever Council for Unity."