Background: An increasing need exists for suitable measures to evaluate treatment outcome in adolescents. YP-CORE is a pan-theoretical brief questionnaire developed for this purpose, but it lacks studies in different cultures or languages.Aims: To explore the acceptability, factor structure, reliability, validity, and sensitivity to change of the Finnish translation of YP-CORE.Methods: The study was conducted at the Department of Adolescent Psychiatry, Helsinki University Central Hospital. A Finnish translation was prepared by a team of professionals and adolescents. A clinical sample of 104 patients was asked to complete the form together with BDI-21 and BAI, and 92 of them filled the forms again after a 3-month treatment. Analysis included acceptability, confirmatory factor analysis, internal and test-re-test reliability, concurrent validity, influence of gender and age, and criteria for reliable change.Results: YP-CORE was well accepted, and the rate of missing values was low. Internal consistency (=0.83-.92) and test-re-test reliability were good (r=0.69), and the results of CFA supported a one-factor model. YP-CORE showed good concurrent validity against two widely used symptom-specific measures (r=0.62-0.87). Gender had a moderately strong effect on the scores (d=0.67), but the effect of age was not as evident. The measure was sensitive to change, showing a larger effect size (d=0.55) than in the BDI-21 and BAI (d=0.31-0.50).Conclusions: The results show that the translation of YP-CORE into Finnish has been successful, the YP-CORE has good psychometric properties, and the measure could be taken into wider use in clinical settings for outcome measurement in adolescents.