The purpose of the study was to examine the student-level and school-level variability that affect middle school students' academic achievement. Student background and school context on student academic achievement were examined. Participants of the study consisted of 1053 seventh and eighth grade middle school students from 10 schools in the cities of Ankara and Sinop, Turkey. The research study analysed using two-level hierarchical linear modeling (HLM). Data were analysed with three HLM models: (1) random effects one-way ANOVA model, (2) random coefficients regression model, (3) intercepts and slopes-as outcomes model. The results of the analyses showed that at the student level, gender, SES, and number of siblings were found to have statistically significant effects on student GPA. When considering the practical importance of student level variables, SES, and number of siblings have small effects, but gender has a moderate effect on students' school achievements. On average, female students perform higher than male students in terms of their GPA scores. At the school level, educational school resources have a significant effect on predicting academic achievement. It has been shown that school resources have a moderate effect on students' academic achievements.