Background: Teacher-related factors such as gender, experience, conceptions related to mathematics, instructional practices have effects with various magnitudes on students' mathematics achievement. Classroom related factors such as class size, class climate and limitations to teaching and their relation to mathematics achievement have also been studied. The TIMSS data provides opportunities to researchers for dealing with these variables simultaneously, thus, makes comparisons in cross-cultural settings. Aim: To develop a multi-level model that investigate the relation of mathematics teacher and classroom characteristics to students' mathematics achievement in the TIMSS-R data across Turkey and European Union (EU) countries. Sample: The target population for TIMSS-R was 13-year-old students at the time of testing. Two-stage stratified cluster sample design was used in TIMSS-R. In this study, the data from 10 countries, namely Turkey, Belgium (Flemish), Italy, Netherlands, Czech Republic, Lithuania, Hungary, Slovak Republic, Slovenia and Cyprus were analyzed. Method: Hierarchical linear modeling (HLM) techniques were employed. Results: Except the home educational resources, no other variable is significant in all the countries. The variables have different impacts with different magnitudes and directions across the countries except reteaching and clarification, class size, class climate and limitations to teaching. Even though the overall findings obtained in the analyses indicated no consistency in line with significant variables in different countries. Conclusion: Findings indicated no overall consistency across the countries. Limitations to teaching, class size and class climate are moderately related to mathematics achievement. Re-teaching and clarification and pair work do not contribute to learning in any country. There is no best teaching method in the classroom, when lecture style, guided practice, independent practice are considered. Emphasize on problem solving in the classroom clearly fosters learning in the European Union countries whereas textbook based teaching is effective in Turkey. (Contains 1 figure and 4 tables.)