As part of the Cambridge Study in Delinquent Development, which is a prospective longitudinal survey, 389 youths were interviewed at age 18-19 and asked to give accounts of fights. A distinction was made between individual fights and group fights. Group fights were associated with frequent fighting and aggressive attitudes. The more aggressive and more frequent fighters came from deprived backgrounds (poor, large families) and had socially deviant lifestyles as young adults (involving delinquency, drug use, sexually promiscuity, and an unstable job record). While the extent of aggression reflected background and lifestyle, the characteristics of any particular aggressive incident depended upon the individual or group social context. Tables, notes, and 15 references are provided. (Author abstract modified)