The Illinois Status Offender Services (ISOS), a part of a nationwide strategy, was designed to provide youths with crisis intervention; brief counseling; and, if necessary, temporary placement in a foster or shelter home as alternatives to secure detention. The study sampled youths from Cook County (primarily the city of Chicago) and Macon County (primarily the city of Decatur). A total of 305 youths served by ISOS between July 1976 and January 1977 were compared with 222 youths placed in secure detention between July 1975 and January 1976. The results showed that institutionalization, or secure detention, and a community-based program for status offenders did not differ in their effects on youths' subsequent contacts with the juvenile justice system. This was true for both status and delinquent offenses. Moreover, with the reduction of status offenses, the relative proportion of delinquencies rose for both detention and alternative groups. The differences were especially marked for males, who changed from a behavioral pattern consisting predominantly of status offenses to predominantly delinquent offenses. Also, although the number of contacts with the justice system following intervention clearly dropped for both groups, the data suggested that maturation was a factor. The findings also indicated that youths arrested for a status offense who were considered detainable tended to be mixed offenders. In the future, evaluations should examine more closely the responses of both individual clients and justice and social service systems to programs designed to affect juvenile misbehavior. Statistical and graphic data, footnotes, and about 20 references are included.