More than one-quarter of clinical trials in the United States fail to enroll a sufficient number of participants, introducing significant delay, cost, and uncertainty in evaluating the merit of promising clinical interventions and research designs. Alzheimer's disease and related dementias (ADRD) trials already face a shortfall of thousands of eligible participants, a number that will rise exponentially as primary and secondary prevention research opportunities develop over the next several years. Given this shortfall, advances in participant recruitment and clinical research design are urgently needed to address barriers to participation. While the identification and quantification of successful recruitment strategy is complex and multi-factorial, the field lacks empirically rigorous models and methods in the science of recruitment, engagement, and retention (RER). These factors are compounded for underrepresented and marginalized populations, and a dearth of peer-reviewed research on the optimization of recruitment tactics hinders our ability to address research recruitment disparities, and slows the pace of science for large observational studies, longitudinal projects, and large-scale clinical trials. Thus, the overarching goal of this proposal is to develop robust mechanisms of efficacy in RER, a basic sciences approach to sustainable and inclusive recruitment into ADRD studies. The current proposal develops this science through deep community canvassing and data mapping tools to establish population norms on RER (Part 1), surveys ADRD research sites to develop innovative, data-driven RER novel metrics and interventions (Part 2), and establishes communications frameworks to improve literacy of RER and ADRD research for both research and lay communities (Part 3). This proposal thus develops, operationalizes, and implements innovative approaches to address challenges in effective research recruitment by advancing a mechanistic, theory-driven emphasis on RER. I focus on participation and recruitment barriers disproportionately experienced by racial and ethnic minorities; LGBT/queer populations; rural residents; native tribal communities; low income neighborhoods; individuals with less than a high-school education, and particularly the intersections of these identities . While this five-year proposal aims to firmly establish a sustainable science of RER for ADRD research, I also aim to leverage these innovations to both build and sustain reciprocal relationships between local, diverse communities and ADRD research study sites to advance progress in dementia research.