Dementia disparities are a major and rapidly escalating public health threat. For instance, Black and Latinx adults are up to three times as likely to develop Alzheimer’s disease (AD) compared to non-Latinx whites (NLW), yet they remain greatly underrepresented in research. Further, underrepresented populations (URPs; e.g., Black, Latinx; low SES) also bear a disparate burden of biological and sociocultural vulnerabilities that confer increased dementia risk, but dementia etiologies and the role of such vulnerabilities remain poorly understood. In addition, community-engaged research (CER) is an evidence-based approach for successful URP recruitment, but has lacked scalability for broad implementation. Further, the lack of an ethnoculturally/linguistically diverse, culturally competent dementia workforce may further exacerbate these challenges. Thus, the 2019 update to the National Plan to Address AD and the NIA Advisory Council (NOT-AG-18-047) have recommended the prioritization of Health Disparities research in AD. ADNI4’s Engagement Core will address these urgent priorities through: 1) increasing the engagement of underrepresented populations in ADNI4; 2) cultivating a diverse, culturally competent workforce to work with URPs; and 3) investigating ethnocultural disparities in dementia. To this end, the Engagement Core will achieve these aims by deploying a scalable, intensive, and culturally-informed CER approach for ~20,000+ individuals (50-60% from URPs) to complete the digital screener to identify 4,000 participants with AD blood biomarkers, followed by either in-person (n = 500; 50-60% URPs) or remote (remainder of the 20,000 not enrolled in clinic) longitudinal evaluations. This Core will work closely with Project 1 and the other ADNI4 Cores to support their aims and assure the full and immersive participation of URPs in all study components. Our comprehensive, multi-faceted plan includes: (1) a CER-based Digital Engagement Campaign; (2) a Diverse Engagement Team, including Community Research Liaisons to promote URP recruitment through community-based engagement with local community-based organizations (CBOs), and Community Research Navigators to promote retention/engagement via providing navigational support to all participants and study partners; (3) Diversity Recruitment Hub Sites (n = 20) that will receive additional fiscal and instrumental support for URP recruitment; (4) Community Partnerships (e.g., national and local CBOs) that will be facilitated through our Community-Science Partnership Board; (5) Culturally-informed Methods to address barriers to URP recruitment/engagement (e.g., trust, burden) and provide better ethnocultural characterization of the sample; and (6) Workforce Training to enhance cultural competency of all ADNI investigators and staff, and provide mentored training to a total 15 ADNI4 Scholars over five years (URP trainees and early career investigators). The activities and goals detailed in this Core are deemed...