This field study features intensive personal interviews of more than four hundred young people who have left home and school and are living on the streets of Toronto and Vancouver. The study examines why youth take to the streets, their struggles to survive there, their victimization and involvement in crime, their associations with other street youth, especially within "street families," their contacts with the police, and their efforts to rejoin conventional society. Major theories of youth crime are analyzed and reappraised in the context of a new social capital theory of crime.