This article explores the pattern of variation in mathematics achievement by Singaporean students. The data were obtained from 4,599 secondary school students who participated in the 2007 Trends in International Mathematics and Science Study (TIMSS). A three-level multilevel linear model was used, for which the results indicate that out of the total variance in mathematics achievement, 23.40%, 53.25%,and 23.34% accounted for student-, classroom-, and school-level differences, respectively. At the student level, mathematics self-concept, home educational resources, and attitude towards mathematics were the strongest predictors of achievement. Meanwhile, at the classroom level, teaching limitations, school climate as perceived by the teachers and teachers’ age were the most influential factors. At the same time, school climate as perceived by school principals and good attendance at school were the most influential factors at the school level.