Sales, Célia M. D.Ashworth, MarkAyis, SalmaBarkham, MichaelEdbrooke‐Childs, JulianFaisca, LuisJacob, JennaXu, DanCooper, Mick2022-04-192022-04-1920220021-9762http://hdl.handle.net/10400.1/17771Idiographic patient-reported outcome measures (I-PROMs) are a growing set of individualized tools for use in routine outcome monitoring (ROM) in psychological therapies. This paper presents a position statement on their conceptualization, use, and analysis, based on contemporary evidence and clinical practice. Four problem-based, and seven goal-based, I-PROMs, with some evidence of psychometric evaluation and use in psychotherapy, were identified. I-PROMs may be particularly valuable to the evaluation of psychological therapies because of their clinical utility and their alignment with a patient-centered approach. However, there are several challenges for I-PROMs: how to generate items in a robust manner, their measurement model, methods for establishing their reliability and validity, and the meaning of an aggregated I-PROM score. Based on the current state of the literature, we recommend that I-PROMs are used to complement nomothetic measures. Research recommendations are also made regarding the most appropriate methods for analyzing I-PROM data.engIdiographic outcomesI-PROMsMeasurement modelPsychometricsRoutine outcome monitoringjournal article10.1002/jclp.23319