Idiographic 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.