Background: Examining the effectiveness and adequacy of adolescents' psychiatric inpatient treatment through multiple perspectives is crucial to provide the best care. Objectives: The aims of the current study were to examine the consistencies and discrepancies between patients and clinicians and to understand how each group considered the timing of improvement of symptoms and psychosocial difficulties of adolescents during a psychiatric inpatient stay. Methods: The Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA, assessing symptoms and psychosocial difficulties) was rated on a weekly basis by patients and clinicians during a psychiatric inpatient stay. Data were collected from 297 patients, 58.2% females. Results: Both clinicians and patients reported a significant decrease of the HoNOSCA scores from admission to discharge, revealing that inpatient treatment is perceived as helping the adolescents to alleviate their symptoms and psychosocial difficulties. However, the item- by-item analyses indicated that patients and clinicians reported difficulties in different symptoms and psychosocial domains. Moreover, the week-by-week analyses revealed discrepancies in the perception of the time- course of clinical outcome-changes between clinicians and patients, as well as between males and females, and between voluntarily and involuntarily admitted patients. Conclusion: By integrating perspectives of patients and clinicians and their respective timelines, as well as by taking into account the mode of admission and the patient's gender, this study provides a deeper understanding of the evolution of clinical outcome during adolescents' hospitalizations, which allows to adapt their treatment and therewith, to help patients more efficiently.