This study aims to investigate the causal effects of school type on the student achievement. Schools type involves two categories: public schools and private schools; whereas student achievement is defined in terms of an overall measure named as Basis for Admission Score (BAS), which is a weighted score reflecting both the grades obtained from courses in each school and the points obtained at nation-wide centralized exams. Factors used as controls in the study include gender of the student, parental attributes (are they alive and live together; their levels of education and occupations), type of the house (own/rent/public housing), separate room of the student, city the family lives in and the level of development of the geographical region. This study utilizes a dataset comprising 3,752,374 secondary school students, which covers all of the student population of Turkish secondary schools within 2014-2016 period. This comprehensive dataset is utilized for the first time in such a study.