This study examines the relationships between pre-, during-, post- treatment variables, and treatment outcome by using a secondary data analysis of the 6- and 12-month posttreatment follow-up data from 2,317 adolescent subjects. Pre-treatment variables included in this study are psychosocial, family-related, substance abuse, and special event variables. During- treatment variables are length of stay and parental participation in treatment. Post-treatment variables cover the attendance of subsequent treatment/continuing care, such as AA/NA and CD aftercare, and parental attendance of subsequent treatment. Results from discriminant function analyses indicated that during- and post-treatment variables could differentiate the abstinence status at 6- and 12-month follow-ups. It was also shown that the posttreatment variable group exhibited the best classification accuracy among the three variable groups across both follow- up periods. Limitations in applying research findings and their implications for adolescent substance abuse treatment are also discussed.