The purpose of this study is to investigate the effects of mathematics teacher and classroom characteristics on students&rsquo / mathematics achievement across Turkey,European Union countries and the other candidate countries by analysing the data collected from student and teacher background questionnaire and mathematics achievement test in the Third International Mathematics and Science Study (TIMSS-R). Mathematics teacher characteristics were divided into three groups as teacher&rsquo / s background variables, teacher&rsquo / s instructional practices and class characteristics. Except Cyprus, in all the other countries, there was sufficient amount of between-class variance to build explanatory models. After home educational resources (HER) of students was taken as a control variable, explanatory models were built by using Hierarchical Linear Modeling (HLM). The amount of variance explained by the full model ranged from 26 % in Romania to 74 % in Netherlands. There were substantial differences among the countries, especially in the teacher&rsquo / s instructional practices. It was found that mean of HER had high effect on student mathematics achievement in all the countries except Romania. It is recommended that the factors that were found to have significant effects on student learning should be explored in experimental settings.