Recent achievement test results show that Turkish students have been performing poorly compared to students from other countries. Using data from the PISA 2006 survey, we aim to measure the determinants of student achievement in Turkey. We find that the program type the student is enrolled in affects student achievement significantly. However, this effect may partially be biased by past academic achievement. In line with the previous literature, our results also indicate that school resources have limited, if any, effect on student achievement. On the other hand, we find that socioeconomic background variables such as parental edu- cation, parental employment, household items, etc. of the student are major determinants of student achievement. Students coming from similar socioeconomic backgrounds enroll in similar schools. To measure possible effects, we use an index of socioeconomic background to calculate an average socioeconomic status within a given school. We find that this has an effect over and above the e®ects of the individual socioeconomic background factors and program types. Therefore, we conclude that any policy design has to take into account the large role of socioeconomic background in determining student outcomes.