The author examined advanced mathematics achievement with 1,839 students from 162 schools. The data were obtained from the Third International Mathematics and Science Study Population 3 cohort; the author used hierarchical (multilevel) linear modeling to examine student- and school-level factors. Even within the advanced mathematics cohort, gender and economic disparities existed, but the magnitude of these disparities varied from school to school. Average parent education was observed to be associated with the magnitude of the coefficient for attitude toward mathematics on achievement. The more a student believed that success in mathematics was caused by natural ability, the higher the score on the test. Finally, resources, school size, and average parent education were significantly associated with school mean achievement in advanced mathematics.