This article explores some of the costs of crime attributable to the typical target of delinquency prevention programs and draws some implications for prevention efforts. Employing data from Delinquency in a Birth Cohort, by Marvin Wolfgang et al., as well as crime data from California, the author estimates the present value of future detected and undetected crime costs attributable to the 1974 population of early minor offenders in California. Early minor offenders are defined as youth whose first offense is a minor or non-index crime. The estimated costs, some social and some private but not all of either, are $930 million. The authors argues that while the sizeable amount would suggest continuing or expanding prevention programs, particularly since most prevention programs show relatively low treatment costs, the ineffectiveness of prevention efforts suggests only small, carefully eval uated programs should be encouraged.