In an era of declining social mobility and growing demand for scientific and technical workers, understanding the process by which students come to pursue mathematics and science programs should be of great concern to governments, employers, and scholars of social inequality. It is long established that socioeconomic background affects educational outcomes and that these class effects operate in part by affecting students' attitudes and aspirations. The present investigation uses data on U.S-American eighth-graders and their schools to explore effects on attitudes of socioeconomic status (SES) measured at the family and school levels. Consistent with previous research pointing to more practical, "instrumental" curricular choices by students from less privileged backgrounds, results show that students from lower-SES families hold more positive attitudes toward math. But multilevel analyses reveal that these attitudes are better predicted by school- than family-level SES. Students in lower-income schools hold more positive attitudes toward math and science regardless of family SES and regardless of individual achievement. The effect of attending a low-income school on affinity for math is especially strong for girls. Findings support arguments suggesting broader cultural effects of affluence on attitudes and aspirations.