Sleep is a robust predictor of child and adolescent development. Race/ethnicity, socioeconomic status (SES), and related experiences (e.g., discrimination) are associated with sleep, but researchers have just begun to understand the role of sleep in the development of racial/ethnic and SES disparities in broader psychosocial adjustment and cognitive functioning during childhood and adolescence. In this article, we discuss poor sleep as a potential mechanism contributing to the development of such disparities, and better sleep as a potential protective factor that diminishes such disparities. We conclude by offering recommendations for research to advance understanding of sleep as a key bioregulatory system that may underlie or protect against detrimental developmental outcomes related to socioeconomic adversity and belonging to a historically minoritized group.