Background: In 2005 a new compulsory residential treatment program was developed for adolescents in need for protection against themselves or their environment. Objective: The aim of the present study was to examine the association of structural treatment characteristics of this new residential treatment program (i.e., duration of treatment, discharge status, and group composition in terms of sex) with post-treatment functioning. Additionally, the number of pre-treatment risk factors was included in the model. Method: A total of 301 adolescents (174 boys, 127 girls), with a mean age at time of admittance of 15.50 (SD = 1.26) participated in this study. The number of risk factors was derived from treatment files of the adolescents at time of entrance. Six months after discharge, adolescents participated in a telephone interview to measure ten post-treatment variables indicating how well they were doing. Results: The results showed that duration of treatment was related to post-treatment living situation, in that adolescents who were in treatment for shorter durations were more likely to live on their own after treatment. For discharge status, findings suggested that adolescents who were regularly discharged had more frequent contact with their family; however, they also showed higher alcohol consumption 6 months after treatment. Group composition was related to the girls' official offending, indicating that girls placed in mixed-sex groups showed significantly fewer official police contacts than did girls in girls-only treatment groups. Conclusion: Overall, structural treatment characteristics were hardly related to the adolescents' functioning after treatment. Suggestions for future research are discussed. (Contains 3 tables.)