This study employed the multiple regression analysis to examine the effects of family characteristics, student characteristics, parental involvement, and school characteristics with regard to learning achievements in mathematics of students of eighth grade in Nepal. Mathematics test was administrated with 762 students (400 girls) of 21 secondary schools in nine districts of three ecological zones-mountain, hill and lowland (tarai). Findings indicated that family characteristics explained the largest amount of variance in mathematics achievement, followed by student characteristics, school characteristics and parental involvement. Variables – parental education, number of books at home, absenteeism, parental support for homework, school type and location, teacher training, the number of school days in the academic year and school physical facilities were significantly related to students’ mathematics achievement. The implications of this study for improving educational quality are discussed.