In the U.S.A., Black/African American adolescents disproportionately experience short and poor-quality sleep, and there is little understanding of why some experience decrements or improvements in sleep over time. Toward conducting culturally specific research and identifying processes that uniquely explain variability within a racial/ethnic group, we utilized a within-group design to examine socioeconomic status (SES) as a predictor of Black adolescents’ sleep. Few studies have examined change-on-change processes in sleep over time. Contributing to the literature in novel ways, we assessed the predictive effect of change in SES over one year on changes in four actigraphy-derived sleep parameters over the same time period. Participants were 218 Black adolescents (Time 1: Mage = 17.09 years; 54.6% female) and their mothers from socioeconomically diverse backgrounds. Adolescents participated in two-waves of data collection spaced approximately one year apart. At each wave, we assessed economic well-being (used to index SES) and sleep using 7 nights of actigraphy from which we derived measures of sleep duration (minutes) and quality (efficiency, long-wake episodes, activity). Latent difference score analyses revealed that adolescents experiencing increases in SES over one year exhibited decreases in both long-wake episodes and sleep activity over one year. Findings suggest that individual differences in change in SES explain individual differences in change in adolescents’ sleep quality. Notably, findings highlight the utility of within-group designs for identifying culturally specific processes that predict improvements in sleep quality in a sample at disproportionate risk for sleep and health disparities.