Background: Educators, researchers and policy-makers worldwide continue to struggle to understand the changes needed for improving educational outcomes and attainment for students, particularly in content areas such as mathematics and science that are essential for developing a highly skilled workforce. Given the continuing emphasis on linking teacher practices with student outcomes, this study aims to explore teachers' use of particular instructional strategies and whether use is associated with student achievement. Methods: Using data from the Trends in International Mathematics and Science Study (TIMSS) 2007, this study examines eighth grade teachers' use of instructional practices that support students' conceptual understanding, and examines the relationship between those practices and mathematics test scores. Data from four countries was examined: U.S., Korea, Japan, and Singapore. Descriptive statistics and a series of multilevel regression models were used. Results: The results show that teachers in the U.S. were most similar to Korean teachers in the frequency and types of teaching practices reported, and that they reported using some practices at least as frequently, or more frequently than teachers in the other countries. A sub-set of teachers' instructional practices are related to mathematics achievement in the U.S. and Singapore, but not in Korea or Japan. Conclusions: Teacher practices explained very little of the variability in test scores, even in cases where particular instructional practices were positively and significantly related to achievement. This research highlights the challenges for examining the teacher-level correlates of student test scores using data from cross-sectional, international studies that do not include measures of students' prior achievement, classroom observations, or estimates of students' out-of-school instruction.