This multilevel study explores the potential relationship between Black-White residential segregation and physical activity. It combines data on physical activity from the 2001 Behavioral Risk Factor Surveillance System (BRFSS), a national telephone survey of adults overseen by the Centers for Disease Control and Prevention (CDC), with a measure of racial segregation. Using hierarchical linear modeling, it controlled for age, sex, Black race, Hispanic ethnicity, education, income, and amount of urban sprawl. For each one-point increase in the Black-White Dissimilarity Index (on a 0-100 scale), the modeled risk of being physically inactive increased by .7% (odds ratio [OR] = 1.007, 95% confidence interval [CI] = 1.003, 1.011). The relationship between segregation and physical activity was similar for Blacks and Whites, though not statistically significant for the Black-only analysis. This finding may imply that the pathway between segregation and ill health includes physical inactivity.