The study, using data derived from an earlier study of alternatives to incarceration for chronic delinquents in Cook County, Ill., consisted of a sample of 1,457 boys who were born in Chicago during 1960 and who were arrested at least once as juveniles by the Chicago Police Department. They were selected randomly from among all members of the 1960 Chicago birth cohort who were ever arrested. The data were collected from the Cook County Juvenile Court and the Chicago Police Department. The dependent variable was operationalized as time-to-next-arrest (one of three basic measures of recidivism), expressed in years and fractions of years. The findings indicate that if court sanctions are analyzed as 'treatment' extending over a period of time, then they are ineffective. However, if court sanctions are analyzed as one-time shocks, in which the event itself produces deterrence, then the results suggest that a short-term effect is achieved. The findings also indicate that the effects of a sanction are not significantly affected by waiting and that being sent to court without a sanction has very little effect on the rearrest rate, if any. Moreover, the effects of imposing a court sanction are well masked; only after the roles of age and prior arrests are factored out does the slowing effect of court sanctions become apparent. Finally, when the microdynamics of 'being on' supervision or probation are examined, some differentiation in outcomes can be determined. It is concluded that sanctions work and that the most effective sanction appears to be the most severe: incarceration, either in a traditional institution or in some other, perhaps more humane, type of residential facility. In addition, the threat of such a sanction can be made to work, but only if rules that involve steadily escalating sanctions are clearly, convincingly, and consistently enforced. Notes are provided for each section. Nineteen tables, 3 figures, and 11 references are included.