Patient-reported outcome measures (PROMs) are instruments that capture patients’ perceptions of their health status and the benefits of treatment. The psychometric adequacy of these tools is therefore an empirical prerequisite. Nevertheless, published evaluations often omit critical details about measurement properties, and clinical trials rarely give a complete account of how PROMs were implemented. To close these gaps, the consensus-based standards for the selection of health measurement instruments (COSMIN) initiative has released version 2.0, a comprehensive update of the original COSMIN 1.0 guidance for PROMs research. This article walks readers through the COSMIN 2.0 checklist, illustrating each item with concrete examples.