BACKGROUND:
Research on rare and undiagnosed diseases is marked by persistent inequities in awareness, access, and participation. The National Institutes of Health sponsored Undiagnosed Diseases Network (UDN) was established to improve diagnosis and discovery for individuals with undiagnosed conditions. To address disparities in access, UDN developed a Community Engagement (CE) model to increase awareness, referrals, and equitable access to diagnostic services through sustained community partnerships.

OBJECTIVES:
To describe the UDN CE model and examine how equity-centered engagement strategies enhance participant access, strengthen community-academic partnership, and inform network-level decision-making.

METHODS:
UDN implemented CE Milestones across 21 clinical sites to support standardized yet locally responsive engagement. Strategies included monthly CE Committee meetings with compensated community partners; site-level training and individualized technical assistance; partnerships with community health centers, advocacy organizations, and faith-based institutions; and co-development of outreach, recruitment, educational materials, and multimedia products. Engagement activities were documented quarterly to capture formats, reach, challenges, and lessons learned.

RESULTS:
UDN documented 102 engagement activities across sites, reflecting expanded partnerships and increased integration of community perspectives. Successes included improved provider awareness, culturally and linguistically tailored outreach, and strengthened referral pathways for potential participants. Engagement was more effective when participant engagement activities were clearly distinguished from community-academic partnership roles, with expectations defined early and communicated consistently. Ongoing challenges included digital access barriers, limited digital and health literacy, translation needs, competing institutional priorities, and skepticism among community providers and families, highlighting the need for sustained trust-building. Equity outcomes included clearer engagement roles, improved documentation, increased emphasis on equity-aligned network sustainability, and growing consensus that advancing equity requires “bringing UDN into the community.”

CONCLUSIONS:
The UDN CE model demonstrates the feasibility and value of equity-centered community engagement within a large, multi-site national research initiative and offers transferable guidance for advancing equitable participation in complex diagnostic systems.