In recent decades, the Black-White test score disparity has decreased, while the test score disparity between children of high- versus low-income parents has increased. This study focuses on a comparison that has, to date, fallen between the separate literatures on these diverging trends - Black and White students whose parents have similarly low, middle, or high incomes (i.e., same-income or race-within-income). To do so, I draw on three nationally representative datasets on ninth or tenth graders, covering the period from 1960 to 2009, all of which contain information on students' math test scores. I find that math test score disparities between Black and White students with same-income parents are to Blacks' disadvantage. Although these disparities have decreased since 1960, in 2009, they remain substantively large, statistically significant, and largest between children of the highest income parents. Further, family and school characteristics that scholars commonly use to explain test score disparities by race or by income have accounted for markedly decreasing shares of race-within-income disparities over time. The study integrates the literatures on test score disparities by race and by income with needed attention to race's historical and continued structural influence, net of parental income, on students' educational experiences and test score outcomes.