Abstract Racial minorities have disproportionate risk for SARS-CoV-2 diagnoses and adverse outcomes including death. Burden of disease in Black populations is likely underestimated due to sub-optimal access to, and usage of, SARS-CoV-2 testing. Serosurveys, which use probability-based methods to select persons for SARS-CoV-2 testing and an accompanying survey, have potential to improve our understanding of population- level burden of disease and risk factors for infection. However, early results from U.S.-based serosurveys indicate sub-optimal participation rates among Black populations, which results in their under-representation in burden of disease estimates and a limited understanding of risk factors for infection. The current project aims to identify barriers and motivations for participation in population-based SARS-CoV-2 serosurveys among diverse Black sub-populations (e.g. by gender, age, and education level). Understanding factors that influence Black people's decision-making about serosurvey participation and how these factors differ by socio- demographic characteristics will allow us to provide tailored recommendations for increasing Black populations' participation in serosurveys and representation in burden of disease estimates. Our interdisciplinary team of epidemiologists, behavioral scientists, and community health advocates/practitioners will use qualitative and quantitative methods in the context of serosurveys to understand how influences on decision-making are related to actual decisions about participation in SARS-CoV-2 antibody testing. Our qualitative interview guide will be informed by the family of value expectancy theories and will be developed in collaboration with a community advisory board (CAB), who will also help us to identify community constituents for participation in qualitative interviews. Key themes from the qualitative interviews, and language used by respondents, will inform a quantitative survey instrument, which will assess relative strengths of influences on serosurvey participation and how they differ socio-demographically across Black sub-populations. Our Specific Aims are: (1) Convene a community advisory board (CAB) comprising leaders from organizations serving Black communities in Atlanta (e.g., professional, faith-based, health and social services); (2) In the context of a SARS-CoV-2 serosurvey, conduct 50 semi-structured interviews about barriers and motivations for serosurvey and vaccine participation with Black persons from 3 diverse neighborhoods, representing a range of socio- demographic characteristics; (3) Determine the distribution of barriers and motivations for serosurvey participation across socio-demographic subgroups of 2,000 Black persons using a quantitative survey. We will provide recommendations for increasing participation of black communities in SARS-CoV-2 serosurveys, which is critical as SARS-CoV-2 serosurveys are likely to be used for on-going disease surveillance in the U.S. ...