This document introduces a framework for professional bodies to assess their progress on diversity and inclusion. It consists of a four-level maturity model and descriptors of good practice across eight areas, including governance, membership, events, education, and employment. Professional bodies can use the framework internally to structure conversations about performance, identify strengths and areas for development, and plan next steps. The document also describes how professional bodies can participate in a collective benchmarking exercise to share good practices and learn from each other.