The ASCENT Measurement Library is an interactive, web-based resource that provides centralized access to measures with potential use in palliative care research. This library is designed to support consistent measurement, promote data harmonization, and identify existing measures relevant to palliative care research across the lifespan. This living document serves as a shared reference point for ASCENT investigators, coordinators, and collaborators to use for planning research, selecting appropriate measures, and/or aligning data collection efforts.