BACKGROUND AND OBJECTIVES: The primary study objective was to examine the association between Social Vulnerability index (SVI) and risk of incident Alzheimer disease (AD) and rate of cognitive decline. METHODS: This is a secondary analysis of data from the Chicago Health and Aging Project, a population-based cohort study. Participants were recruited through door visits, were at least 65 years of age at enrollment, and lived in one of 4 Chicago communities representing 24 US census tracts. The association of SVI with clinically diagnosed incident AD was examined using a logistic regression model and global cognitive decline using a linear mixed-effects model. RESULTS: A total of 6,781 participants were in this study, with a mean age of 72 years, representing over 60% Black participants and over 60% female participants, and with a mean of 12 years of education. Over 90% of Black participants were in tracts above 50% or higher SVI, and approximately 87% of White participants were in tracts with SVI 50% or less. Participants in tracts with SVI above 50th to 75th percentiles had OR = 2.23 (95% CI 1.23-4.05) for clinical AD, and participants in tracts greater than the 75th percentile had OR = 2.04 (95% CI 1.03-4.04). Participants in more vulnerable tracts had greater incident AD risk than participants in less vulnerable tracts. The annual rate of global cognitive decline was 0.055 SD units (SDU) for participants below the 25th SVI percentile. The annual rate of global cognitive decline was faster by 0.010 SDU (approximately 18% faster, DISCUSSION: Most Black participants who lived in areas with higher SVI that had over twice the risk of incident AD than most White participants who lived in areas with lower SVI, showing a higher social burden in Black older adults. There was no statistically significant race difference in incident AD after adjusting for SVI. SVI should be accounted for when examining race differences in AD.