Given math-related fields are still highly racialized and gendered (NCSES, 2021), this study assessed: 1) whether there were racial differences in adolescents’ perceived math cost alongside expectancies and values and 2) the extent to which perceived math cost alongside expectancies and values explained yearly changes in achievement differences by race and gender. This study assessed 2,338 Black (39.4 %) and White (60.6 %) adolescents, roughly half girls (47.8 %), in the 6th to 12th grades (M = 14.71 years old, SD = 1.93, 61.7 % qualifying for free or reduced priced lunch). The results indicated that Black adolescents perceived higher costs to learning math than their White peers but value math in similar ways. Perceived math cost was the only motivational belief to explain achievement differences between Black and White girls but not boys after adjusting for socioeconomic status and grade level. In contrast, perceptions of ability beliefs explained achievement differences between Black boys and girls. These findings point to the importance of employing intersectional approaches to understand the relationship between math motivation and achievement.