New York's Juvenile Offender Law (JO) requires that juveniles who commit violent offenses be tried in criminal court and be subject to adult penalties. It has been called the most punitive delinquency law in the United States. Monthly arrest totals reported by New York City and upstate New York jurisdictions are analyzed for individuals aged 13 to 15 for the five crimes of homicide, rape, robbery, assault, and arson. The arrest statistics studied cover the period between January 1974 and December 1984 and are derived from the Uniform Crime Reporting Division of the FBI. Interrupted time series analysis is used because it has been identified as one of the strongest quasi-experiments and can be controlled for most threats to the validity of inferences drawn from it. The study concludes that the strong New York JO law did not deter juvenile crime, and policy implications of this finding are discussed. 14 footnotes and 26 references.