The purposes of this study are to investigate how mathematics achievement can be explained in terms of motivational beliefs (intrinsic goal orientation, extrinsic goal orientation, task value, control and learning beliefs, self efficacy for learning and performance and test anxiety), self-regulated learning components (cognitive strategy use and self-regulation), gender and school types and to determine the differences between two gender (girls and boys) and two school types (public schools and private schools) with respect to the variables above in the subject domain of mathematics. The study was conducted in Istanbul and Ankara, two largest cities of Turkey. Motivated Strategies for Learning Questionnaire (MSLQ) and Mathematics Achievement Test (MAT) were used. By using Linear Stepwise Regression and MANOVA, some important resuts were reached. One of these results is that the combined effect of three predictor variables (school type, self-efficacy and intrinsic goal orientation) on students’ mathematics achievement was significant. In other words, school type, self-efficacy and intrinsic goal orientation are important in mathematics achievement.