OMERACT working groups are dedicated teams focused on developing Core Outcome Sets (COS) or related methodologies. These groups, composed of clinicians, researchers, methodologists, and patient research partners, work collaboratively to ensure that the COS and methodologies they create are meaningful, reliable, and adaptable. By establishing standardized outcomes and robust methods, OMERACT working groups enhance the quality and consistency of clinical trial measurements that are both scientifically sound and aligned with patient priorities.