This research aims to study the internal factors and external factors affecting string students' academicachievement. Quantitative and qualitative methodologies were used in the study. The structured questionnaire wasused in the quantitative data gathered from purposive sampling of 53 pre-college western string students of theCollege of Music, Mahidol University enrolled in the second semester of the academic year 2014.Quantitative statistical analysis was presented by frequency. For qualitative data, content analysis method wasemployed. The results are as follows: factors affecting both successful string students and regular studentsû academicachievement include goal setting in each semester, participation in music master class and concerts, selfmotivatedstudy of background and detail of the piece, conscientiousness, invested mentors, caring and supportiveparents being able to apply knowledge from theory subjects in practice. However successful string students differ intwo areas, they practice more than 21 hours per week and are interested in taking part in music competitions.Keyword: Music students; String music instruments; Factors affecting achievemen