Introduction: The present study examined parents’ and adolescents’ perceptions of adolescent functioning after being discharged from residential treatment as well as the stability of functioning over time. Method: Data for the study were collected as a part of a continuous process of evaluating post-treatment functioning. Adolescents and their parents were interviewed at home at 3 months (T1), 6 months (T2), and 18 months (T3) after discharge. Several outcomes were evaluated: living situation, contact with parents, social network, school/work, behavior problems, use of soft drugs, police contacts and well-being. The sample was divided into two sub samples: parents (n = 82) and adolescents (n = 75) participating in all three waves (sample 1) and parents (n = 288) and adolescents (n = 317) participating in at least one wave (sample 2). Results: Cautioned by the inevitable high rates of attrition and the risk of selective bias in this type of study, there is preliminary evidence showing that adolescents generally show positive outcomes after residential care. Moreover, the outcomes were stable over time: adolescents who showed positive outcomes directly after discharge also showed positive outcomes at T2 and T3, and vice versa. Parents reported less positive outcomes than adolescents did. Discussion: An important contribution of this study is that it provides longitudinal data supporting the notion that outcomes from residential treatment may be more sustainable over time than previously thought. Clinical and research implications are discussed.