Children violently express anger soon after birth and are sufficiently well coordinated to hit, bite and kick before their first birthday. By the time children reach the age of three, they are capable of a wide range of acts of physical aggression. For most children, the use of aggression starts to decline after toddlerhood, as they learn to control their emotions, communicate through language, and express their frustrations in a more constructive way.

This report examines what we know about aggressive behaviour among our youngest citizens. Against the backdrop of recent research on childhood development, the evidence is growing clear: childhood aggression must be taken seriously. The research literature demonstrates that interventions with aggressive adolescents often substantially increase the likelihood of criminal behavior while interventions with at-risk preschool children have long term beneficial effects.