Project Confirm uses two primary strategies to reduce the unnecessary detention of foster care children who are arrested: notification and court conferencing. The notification component involves determining whether a juvenile arrestee is in foster care; and if so, project staff provides the name and phone number of the child welfare caseworker to the juvenile justice official, followed by notification to the caseworker. Court conferencing is then conducted to ensure that child welfare representatives and their counterparts in the juvenile justice system know their responsibilities in a case that involves a foster care juvenile. The outcome evaluation sought to determine whether Project Confirm reduced the difference in detention rates between nonfoster care juveniles and foster care juveniles. A related issue was whether Project Confirm reduced the difference in detention more for some groups than for others. The database for the evaluation involved matching administrative data from the child welfare and juvenile justice systems for the years 1997 to 1999. This permitted determining whether a juvenile was in foster care when he/she was admitted to detention. Logistic regression compared detention rates of the groups before and after Project Confirm. The evaluation found a difference in preadjudication detention rates between foster care and nonfoster care juveniles with similar characteristics both before and after the introduction of the program. The lack of an average program effect on detention rates for the two groups is explained by the fact that the difference decreased for juveniles with less serious records but increased for those with more serious records. Both the difference in detention prior to the programs and the program effect differed according to juveniles' gender, race, and the county where the case was processed. 6 tables, 13 notes, and 25 references