Five to eight percent of children in all populations have problems with aggression, a remarkably persistent personality characteristic, with aggression at age eight reliably predicting adult criminality. We need to know more about risks for childhood aggression and resilience in the face of such risks. However, perhaps eighty percent of boys from the worst inner-city neighborhoods are arrested for a crime by the age of 18. This is a different problem from aggressiveness in early childhood, poses different research challenges, and requires wholly different responses from society. More research on the circumstances of poor families, the experiences of their children growing up and as young adults, and their opportunities for participation in mainstream society is necessary to inform interventions at the level of the individual, the community, and the society.