Abstract This research aims to identify and quantify the relative impact of key factors influencing mathematics student performance in Bac Giang province, Vietnam. A quantitative research design was employed, utilizing a survey instrument based on a 5-point Likert scale. Participants included 500 mathematics students from 40 high schools in Bac Giang. Data analysis involved Cronbach's Alpha for reliability, Exploratory Factor Analysis (EFA) to identify underlying factors, and Ordinary Least Squares (OLS) regression to assess relationships with self-reported student performance, which, it must be noted, was also measured using a Likert Scale. The EFA revealed five key factors: Teacher Quality, Student Motivation, Learning Resources, Parental Involvement, and Classroom Environment. The OLS regression model was statistically significant, explaining 66.3% of the variance in self-reported student performance. All five factors were statistically significant positive predictors, with Teacher Quality demonstrating the most substantial relative impact. The findings highlight the multifactorial nature of perceived mathematics achievement and suggest that interventions targeting teacher quality, student motivation, resource provision, parental engagement, and classroom environment are likely beneficial. However, the reliance on self-reported performance as the dependent variable is a significant limitation, and future research should incorporate objective achievement measures. These results, nevertheless, provide a data-driven basis for pedagogical and policy recommendations in Bac Giang's specific context. Keywords: Mathematics Education, Student Performance, Bac Giang, Self-Reported Achievement, Factor Analysis, Regression Analysis.