We examine racial disparities in upward intergenerational mobility of family income by linking American Community Survey respondents born in 1978-87 to their parents’ tax records. This linkage facilitates better measurement of marriage-market processes than tax records alone. Relative to White individuals, we document lower upward mobility of partner income for Black, Hispanic, and Asian individuals. These disparities offset Asian women and men’s advantages in personal income mobility, overturn Black women’s small advantage, and compound Black men’s disadvantage. We develop a novel nonparametric decomposition which reveals that these disparities are driven primarily by racial differences in marriage-market opportunities, but also by different partnering rates conditional on opportunities. We then apply a selection-correction methodology to estimate causal effects of childhood exposure to racial segregation. Our design approximates a shift in the current generation’s segregation exposure, holding historical exposures constant. This channel generates substantial Black-White intergenerational mobility gaps across all income measures, and we show that these effects cumulate over a multigenerational horizon.