ABSTRACT This study uses measurement-based care (MBC) to examine patient improvement and trajectories of change during treatment in an adolescent partial hospitalization program (PHP). The current study also explored whether youth trajectories in PHP varied based on demographic variables, symptom severity at intake, or presence of an anxiety or depressive disorder diagnosis. Participants included 124 youth (aged 13–18) with primarily anxiety and depression diagnoses who received care in a PHP. The Top Problems Assessment (TPA), an idiographic measure of patients’ chief complaints, was administered weekly alongside depression and anxiety symptom questionnaires to incorporate the consumer perspective. Results demonstrated that youth significantly benefitted from PHP treatment across all measures. The rate of TPA improvement slowed down over time, whereas rates of decline for anxiety and depression questionnaires did not change statistically. Anxiety disorder status and more severe baseline anxiety symptoms were also independently associated with slower rates of improvement on TPA, but not on the symptom measures. Overall, these results suggest youth improved from treatment in this PHP and that changes in youth-reported top problems may be more prominent at the beginning of treatment. Moreover, providers may want to consider treatment modifications, or perhaps monitor progress more closely, for youth who present with higher anxiety severity at PHP admission. This study demonstrates how incorporating MBC practices and personalized assessment in a PHP can enable exploration of who benefits most, under what conditions, and when.