This study draws on data from 77 and 68 educational systems to conduct a meta-analysis examining the relationship between students’ cultural capital, teacher support, student–teacher relationships, and mathematics achievement. Results show that objectified and institutionalized forms of cultural capital—specifically home possessions (r = .27, p < .0001), parental occupational status (r = .17, p < .0001), and parental education (r = .02 to .03, p < .0001)—are positively associated with student performance, though the strength of these associations varies substantially across national contexts (I² = 84%–90%). While teacher support (TEACHSUP) and student–teacher relationships (RELATST) do not show significant direct associations with achievement, interaction analyses indicate small but statistically significant moderation patterns. Specifically, teacher support is associated with slight variation in the relationship between home possessions and occupational status and achievement, while student–teacher relationships show similarly modest associations with parental education and home possessions. These effects are small in magnitude (r = .01 to .04) and should be interpreted with caution. Taken together, the findings do not provide clear evidence of compensatory effects and are consistent with multiple interpretations, including slight variation in existing socioeconomic gradients. The results highlight the continued importance of structural resources as the most consistent predictors of achievement and suggest that the equity potential of relational interventions should be interpreted cautiously.