The author studies boys' gangs through interviews and observation, using accounts from dozens of boys to trace how groups form, organize, and behave. He describes common structures—names, officers, initiation rites, meeting places—and recurring activities such as games, pranks, theft, migration, truancy, theater-going, and fighting. Drawing on evolutionary and psychological ideas, he argues that many impulses are instinctive survivals that can be directed rather than suppressed. Practical chapters recommend educational responses, playgrounds, workshops, and rules that channel predatory and tribal energies toward cooperative, constructive pursuits.