Geoffrey Canada, director of Rheedlen Centers for Children and Families in New York City, holds his hands out in front of his chest, patting the air tentatively. "This is how people approached a fight between girls," he says. "They would say, 'Come on, you all.' They just wouldn't intervene."

Canada describes how teachers he supervised when he was principal of an inner-city Boston high school seemed hesitant and confused when approaching fights between girls. "I spent particular time training men and women to break up a fight between girls," he says. "Even after we went through it, they wouldn't do it. They just wouldn't do it."

Canada could have been describing the reaction of society at large to girls' violence, say experts in juvenile justice and violence-prevention programs. U.S. Department of Justice statistics show that girls account for a significantly larger proportion of violent juvenile offenses than they did 25 years ago. Yet there has been almost no increase in the number of studies and services devoted to girls and violence.