I: What's going on with girls? -- The new American girl gets physical -- To hit or not to hit: are girls and boys wired differently for aggression? -- II: How is culture changing the lives of girls? -- Girls unleashed -- From powder puff to powerpuff girls: how pop culture celebrates aggressive girls -- The evolution of mean: the new language of girl violence -- III: When things go from bad to worse for girls, then and now -- Cinderella strikes back: girls who are sad, mad, and hurt -- Girls who kill ... themselves or others -- IV: What now? -- Lifelines and safety nets: helping girls get physical without getting hurt or hurting other people -- Female aggression in the twenty-first century: what lies ahead for the new American girl?.