The purpose of this study was to investigate the effects of student-level and school-level variables on mathematics achievement in four countries including Finland, South Korea, Taiwan, and Turkey. Based on eighth grade students’ responses to a student questionnaire and a mathematics test, and school principals’ responses to a school questionnaire, the Trends in International Mathematics and Science Study (TIMSS) 2011 dataset was analyzed using Hierarchical Linear Models. The results revealed that students’ having educational resources at home, their self-confidence in mathematics, and schools’ emphasis on academic standards were the common variables that influenced mathematics achievement in all four countries. On the other hand, no significant effects of education levels of parents (except education levels of mothers in Turkey), fights or physical injuries to other students, and lack of resources for mathematics instruction on students’ mathematics achievement were found in these countries. Implications of the results are discussed.