“My eyes rolled immediately when I heard what the model was,” says Webster of Johns Hopkins, who is studying the Baltimore project. Webster knew the forces the interrupters were up against and considered it wishful thinking that they could effectively mediate disputes. “But when I looked closer at the data,” Webster continues, “and got to know more about who these people were and what they were doing, I became far less skeptical and more hopeful. We’re going to learn from it. And it will evolve.” George Kelling, a Rutgers professor of criminal justice who is helping to establish an effort in Newark to reduce homicide, helped develop the “broken window” theory of fighting crime: addressing small issues quickly. He says a public-health model will be fully effective only if coupled with other efforts, including more creative policing and efforts to get gang members back to school or to work. But he sees promise in the CeaseFire model. “I had to overcome resistance,” Kelling told me, referring to the introduction of a similar program in Newark. “But I think Slutkin’s on to something.”

Most of the police officials I spoke with, in both Chicago and Baltimore, were grateful for the interrupters. James B. Jackson, now the first deputy superintendent in Chicago, was once the commander of the 11th district, which has one of the highest rates of violent crime in the city. Jackson told me that after his officers investigated an incident, he would ask the police to pull back so the interrupters could mediate. He understood that if the interrupters were associated with the police, it would jeopardize their standing among gang members. “If you look at how segments of the population view the police department, it makes some of our efforts problematic,” Baltimore’s police commissioner, Frederick H. Bealefeld III, told me. “It takes someone who knows these guys to go in and say, ‘Hey, lay off.’ We can’t do that.”

Like many new programs that taste some success, CeaseFire has ambitions that threaten to outgrow its capacity. Slutkin has put much of his effort on taking the project to other cities (there’s interest from Los Angeles, Oakland and Wilmington, Del., among others), and he has consulted with the State Department about assisting in Iraq and in Kenya. (CeaseFire training material has been made available to the provincial reconstruction teams in Iraq.) Meanwhile, their Chicago project is underfinanced, and the interrupters seem stressed from the amount of work they’ve taken on.

THE INTERRUPTERS have certain understandings. At the Wednesday meetings, no one is ever to mention anyone involved in a dispute by name or, for that matter, mention the name of the gang. Instead they refer to “Group A” or “Group B.” They are not investigators for the police. In fact, they go out of their way to avoid knowing too much about a crime. When Highsmith and Prater left me the night of the failed drug deal, they began working their contacts. Highsmith found someone who knew one of the stickup men and who, at Highsmith’s request, negotiated with them. Highsmith’s contact persuaded the robbers to return enough of the money to appease the drug-buyer’s anger. When I met with the intermediary a few weeks after things were resolved, he was still stirred up about the robbery. “I was mad enough to do anything,” he told me, making it clear that he and his friends had been hunting for the stickup guys. “This could’ve been a hell of a lot worse than it was.” To this day, neither Highsmith nor Prater know the identities of anyone except the intermediary  and they want to leave it that way.

The interrupters often operate by instinct. CeaseFire once received a call from the mother of a 15-year-old boy who wanted out of a gang he joined a few weeks earlier. The mother told Hoddenbach and another interrupter, Max Cerda, that the gang members chased her son home every day from school threatening to beat him. They had shot at him twice. Hoddenbach found the clique leaders and tried to talk sense to them. If the boy didn’t want to be in the gang, he told them, he’d be the first one to snitch. The gang members saw the logic behind that but insisted on giving him a beating before releasing him. Hoddenbach then tried another tack: he negotiated to let him leave the gang for $300  and no thrashing. The family, though, was only able to come up with $50, so Hoddenbach, Cerda and another interrupter came up with the rest. At their next Wednesday meeting, some interrupters were critical of Hoddenbach for paying what they considered extortion money. “It was kind of a messed-up way, but it was a messed-up way that works,” Hoddenbach said.

It was nearly three months before Charles Mack could find time to visit Frederick, the young shooting victim. Frederick had since moved in with his great-grandmother in a different part of town. In his old neighborhood, he told Mack, “there always somebody who knows you. And I had a reputation.” He complained to Mack that he had never been interviewed by the police but then declared he would never identify the person who shot him anyway. “I’m going to leave it alone,” he said. As is so often the case, Frederick couldn’t remember the genesis of the disagreement between his clique and the other. Mack promised to stay in touch, and as we dropped him off, Mack turned to me and said, “I think he’s going to be all right.” It sounded like both a proclamation as well as hopeful aside.

Not long ago, I stopped by to visit with Hoddenbach at the Boys and Girls Club, where he holds down a second job. It was a Friday evening, and he was waiting for an old associate to come by to give him an introduction to a group of Hispanic kids on the far North Side. Apparently, earlier in the week, they bashed in the face of an African-American teenager with a brick. From what Hoddenbach could make out, it was the result of a long-simmering dispute  the equivalent of a dormant virus  and the victim’s uncle was now worried that it would set off more fighting. As we sat and talked, Hoddenbach seemed unusually agitated. His left foot twitched as if it had an electric current running through it. “If these idiots continue,” he told me, “somebody’s going to step up and make a statement.”