The aim of this study was to investigate differences in attitudes towards mathematics, mathematics anxiety, and mathematical achievement due to sex, and school type, and to display how well anxiety and attitude towards mathematics determine students’ mathematical achievement controlling for sex and school type. Attitude and anxiety mathematics scales were administered to 307 tenth grade students (128 private and 179 government) and the data collected were analyzed using statistical techniques of mean, standard deviation, independent samples t-test and multiple regression analyses. Results revealed significant differences in attitude, in anxiety and in mathematics scores with respect to type of schools, but no significant sex differences with respect to private schools, government schools and both types of the schools combined together. The multiple regression analysis displayed that sex, school type, attitude towards mathematics and mathematics anxiety had statistically significant contribution on students’ mathematics achievement explaining 45.8% of the variance in mathematics achievement. Of the variables treated in the study, attitude towards mathematics and mathematics anxiety were the best predictor variables of the student mathematics achievement. Based on the findings, valuable suggestions were forwarded for stakeholders. Thus, to decrease the students’ negative attitude towards mathematics and mathematics anxiety students, parents, teachers, school administrators and education planners work together cooperatively; government schools learn best practices from private schools especially in the use of instructional time and teachers create student-centered teaching methods.