The Offspring Study of Racial and Ethnic Disparities in Alzheimer’s Disease began in 2017 to identify biological and sociocultural mechanisms of disparities in cognitive function among middle-aged people with and without a parent with Alzheimer's Disease (AD). This article outlines the objectives and design of this prospective cohort study aimed at advancing the understanding of risk factors among middle aged offspring in order to clarify pathways to AD, and provides background on recruitment and retention of this diverse cohort.