IN THE WEEKS and months after the Columbine tragedy, the nation focused on determining the causes of school violence. TV stations aired special reports, magazines published numerous articles, and newspapers explored the issue with their best reporters. People sought to understand the problem and searched for someone or something to hold responsible.

Many immediately blamed abusive homes, crime-ridden neighborhoods, hostile cultures at schools, and students' easy access to drugs and alcohol. These are commonly known as risk factors because they seem to put children at risk for becoming violent. Researchers and observers alike attempted to explain the incidents of school violence by assigning them specific risk factors. Assigning blame to one particular risk factor, however, is impossible, because not all young people who experience a particular risk factor in their lives end up committing violent acts. For example...