States were classified according to whether adult status was reached at age 16, 17, or 18 in each of the years 1970-76. Arrest data were obtained from the 1970-76 Uniform Crime Reports, and data on self-reported offenses were obtained from a nationwide representative sample of 1,116 13-18 year-olds (the 1972 National Survey of Youth). Comparable serious felonies were selected for analysis from the two data sources. Ratios were computed by age groups for arrests and self-reported offenses to control for the potential differences between States that set different ages for juvenile and adult statuses. The study's hypothesis was that youth defined as adults will have lower arrest rates and lower rates of self-reported offenses than youth defined as juveniles due to the more severe sanctions involved. The data suggest that the deterrent effect of adult versus juvenile status cannot be considered independently of the response of the justice system to the offender. Adult status apparently has a deterrent effect on delinquent behavior for the older youth (17 year-olds), but it did not have the same deterrent effect on 16 year-olds. The adult law enforcement system may be reluctant to handle 16 year-old felons as harshly and formally as older youths. This suggests that attempts to use the greater severity of sanctions inherent in adult status to deter juvenile crime could backfire if the minimum age for adult status is set too low. Adult status can serve as a deterrent to juvenile crime, but only for youth who are 17 or older. Tabular data and 14 references are provided.