The study found that only 1 in 10 of the 221 males and females who committed sex offenses as juveniles also committed a sex-related offense during the first 8 years of their adulthood. Another finding showed that 92 percent of all the cohort males with adult records of sex offenses had no record of a prior sex offense as a juvenile. A third finding was that a male juvenile with no contacts with police for sex offending, but with five or more police contacts for other delinquent acts, was more than twice as likely to commit a sex crime as an adult compared to a juvenile sex offender with fewer than five total police contacts as a juvenile. In addition, multinomial logistic regression results showed that being a juvenile sex offender did not significantly increase the likelihood of an individual becoming a sex offender as an adult, nor did the frequency of juvenile sex offending. In drawing implications of these findings for policies toward sex offenders, the authors argue that the assumption of juvenile to adult sex offending careers underlying current sex-offender registration and notification laws should be re-examined for their validity. Study data were from the 1958 Second Philadelphia Birth Cohort, which was composed of 13,160 boys and 14,000 girls. This cohort was followed through age 26. The study relied on police data pertinent to the characteristics and frequency of offending through the juvenile years (through age 18) and into the first 8 years of adulthood (through age 26). 3 tables, 1 figure, and 50 references