The paper tried to clarify factors influencing academic achievement of primary students in mountain-ous areas of Vietnam. The Vietnamese government has focused on the improvement in the quality ofprimary education especially after the quantitative expansion of enrolment rate, which has exceeded90%.0 As one of criteria of the quality of education, students' academic achievement was investigated inthe paper, because academic achievement is most often cited as a school effectiveness indicator byschool principals, teachers, students and their parents (Gaziel, 1996).The data collection was done by the use of questionnaires administered to 95 primary school studentsin mountainous areas. This was statistically analyzed and the result showed that three factors had adirect effect on students' self-reporting of academic achievement. The strongest factor is students' pro-ficiency in Vietnamese, and the next is parents' interest in child's study followed by the existence ofclose friends in school.