Aggressive and violent behaviour among female youth has emerged as a pressing social issue. Girls are entering the juvenile justice system for violent offenses at substantially higher rates than five or ten years ago. Unfortunately, our ability to gauge risk for violence among female youth is less than optimal, mainly because research has focused on identifying risk factors that predict violence and aggression in boys. Consequently, unique risk factors in girls may go undetected. Psychopathy is a powerful predictor of future violence in adult male prisoners, and is characterized by a callous disregard for others, a lack of empathy, and a propensity to highly impulsive and irresponsible behaviour. Despite the important role of psychopathy in violence risk prediction, little research has examined whether the construct of psychopathy applies to females, and virtually no studies have focused on female adolescents. Stephanie Penney is investigating how well psychopathy predicts future violence in girls compared to boys. Stephanie is examining how development, early socialization and environmental influences converge to create risk for females. This research will identify unique risk factors that predispose girls to aggressive and violent behaviour, and can be used to develop early intervention programs to reduce violence among high-risk girls.