The purpose of this study is to investigate the effects of several student and school level variables on students' mathematical achievement and mathematical achievement growth in middle school. The research population consisted of students in Ankara who started middle school in 2008 and graduated in 2011. Using a non-random typical case sampling method, 3715 students were sampled from 40 middle schools. The data used in this study were obtained from the Ministry of National Education with express written permission. Student Placement raw mathematics subtest scores from 2009 to 2011 were used as the dependent variable in the analysis. "Gender, mathematics grade point average in 6h grade, and school attendance at sixth grade" comprised the student level variables whereas "school type and school size" variables comprised the school-level variables. A three-level hierarchical linear growth model was used to investigate the effects of these variables. Students' raw mathematics subtest scores in Students Placement Test were included in the model after these scores were equated. The results of the model analysis indicated that there was no growth in students' mathematical achievement. It was also observed that school attendance, sixth-grade mathematics grade point average and school type had a statistically significant effect on students' sixth-grade mathematical achievement.