Meta-analytic reviews of sex differences in aggression from real-world settings are described. They cover self-reports, observations, peer reports, and teacher reports of overall direct, physical, verbal, and indirect forms of aggression, as well as (for self-reports) trait anger. Findings are related to sexual selection theory and social role theory. Direct, especially physical, aggression was more common in males and females at all ages sampled, was consistent across cultures, and occurred from early childhood on, showing a peak between 20 and 30 years. Anger showed no sex differences. Higher female indirect aggression was limited to later childhood and adolescence and varied with method of measurement. The overall pattern indicated males' greater use of costly methods of aggression rather than a threshold difference in anger.