Background/Context: East Asian schools receive much attention for the comparatively high achievement of their students. To account for this success, scholars and commentators advance broad claims about the rote character of instruction or the complexity of classroom practice, typically generalizing to an entire nation. Yet little is known about the variation in classroom practices within East Asian countries and how classroom organization affects student achievement. Purpose/Objective/Research Question/Focus of Study: This study extends the previous literature on East Asian classrooms by considering the heterogeneity of classroom organization within societies. It focuses on four aspects of classroom instructional practice: complex instruction, procedural instruction, teacher-centered instruction, and student-centered instruction. This study asks the following research questions: (1). To what extent do classroom instructional practices in East Asian countries differ in terms of overall prevalence and within-country variation, compared with to practices found in other nations? (2). How are classroom instructional practices associated with student achievement within East Asian countries, controlling for student, classroom, and school background variables? Research Design: Drawing from the Trends in International Mathematics and Science Study (TIMSS) 2007 data, I examine how the country means and within-country variation of the four aspects of classroom instructional organization in five East Asian countries--Chinese Taipei, Hong Kong, Japan, Korea, and Singapore--compare with those in the other 45 nations in the sample. Then, I focus on two particular East Asian countries that display vastly different school structures, Japan and Singapore, to examine how classroom practices covary with student achievement within these nations. Findings/Results: East Asian classrooms do tend to be more intensely teacher-centered and display less complexity than in other nations on average. But classrooms with more complex and student-centered instruction within East Asian societies display higher achievement; an opposite association is found when comparing between-country relationships worldwide. At the same time, these positive effects observed in East Asia diminish when characteristics of schools and the social-class backgrounds of students are taken into account, similar to patterns long observed in the West. Conclusions/Recommendations: While classroom practices prevalent in East Asian countries are often celebrated as predictive of stronger achievement--or criticized for their rigidity and not importable to the West--these findings reveal greater variability than previously understood and suggest that classroom practices interact with social-class backgrounds and student achievement in more complex ways. And East Asian nations face educational challenges similar to those observed in the United States and other developed countries. Once we acknowledge the commonality as well as the differences, cross-national research would allow us not only to better understand perennial educational problems and the assumptions we hold about classroom practices, but also inform valid implications for policy and practice.