In 19th century rural America, crime and delinquency prevention was handled informally by families, schools, churches, and, as a last resort, the police and courts, often through informal dispositions. Urbanization has increased dependence upon criminal justice and social service professionals for crime prevention. In recent years, policymakers have emphasized cooperative crime prevention efforts that involve lay citizens as well as criminal justice and social service agencies. Citizen crime prevention tasks can include volunteer direct service roles, advocacy, dispute mediation, self-help and mutual-help service, and public education. Measures that promote and enhance citizen involvement are incentives, recruitment, screening, training, and supervision. 28 notes and 9-item bibliography.