OBJECTIVE: The Outcome Measures in Rheumatology (OMERACT) Vasculitis Working Group aims to develop composite response criteria for ANCA-Associated Vasculitis (AAV). METHODS: The project follows the OMERACT approach for composite measures: (i) choose relevant domains; (ii) define high-quality instruments; (iii) decide on a scoring system approach; (iv) put through the OMERACT Filter 2.1 for validation. RESULTS: A systematic literature review of outcome measures used in clinical trials in AAV and an international Delphi exercise among patients with AAV and clinician-investigators with expertise in AAV have been completed to inform the candidate domains/instruments for the composite response criteria, which are the first two steps in the OMERACT approach for developing composite measures. Results of the systematic literature review and Delphi were presented at the OMERACT 2020 virtual workshop, and feedback was received on the next steps of the project, including the development of a scoring system approach. CONCLUSION: The ultimate goal of this project is to develop validated composite response criteria for use in clinical trials of AAV.