The aim of the study is to examine the achievement of secondary school students in mathematics courses based on psychological resilience and academic grit. In the research, descriptive survey model, one of the quantitative research methods, was used. In these places, data were collected from 102 students who attended the joint schools in Kocaeli in the 2022-2023 academic year. The study was based on taking volunteer individuals and informed consent was obtained from the people before participating. Appropriate expenditure was selected from the purposeful spending methods in measuring the study group. As a data collection tool to determine the limits of resilience and academic grit in children, the one-dimensional Brief Resilience Scale adapted by Smith et al. and Dogan (2015) was developed by Clark and Malecki (2019) and Sağkal et al (2020) one-dimensional "Academic Grit Scale" adapted into Turkish was used. In this study, students' mathematics achievement was determined according to the grades in the mathematics course at the end of the semester. Preliminary analyzes were made to examine the characteristics of the scales used and the assumption of normality. As a result of the reliability analysis performed to measure the reliability of the scales, the Cronbach Alpha coefficient of the Brief Psychological Resilience Scale was found to be =0.818 and the Cronbach's Alpha coefficient of the Academic Grit Scale was found to be =0.866. While analysis of variance (ANOVA) and t-test were used for group comparisons, correlation analysis was used to determine the relationship between psychological resilience and academic grit levels. All data analyzes were performed using the SPSS 23 statistical software program. According to the research results, it was seen that the psychological resilience levels of the students were medium and their academic grit levels were medium. Although there was no statistically significant difference in the evaluations made in the context of mathematics course achievement, it was observed that the achievement of the course increased as the levels of psychological resilience and academic grit increased. In terms of different variables, it was seen that academic grit levels did not differ according to gender. It was determined that the psychological resilience levels showed a statistically significant difference according to the gender variable and the psychological resilience of male students was higher. It was observed that the levels of psychological resilience and academic grit did not differ according to grade levels. It was observed that there was a positive and moderate relationship between secondary school students' achievement in mathematics course, psychological resilience levels and academic grit levels. In addition, it was determined that there was a positive and moderate relationship between students' psychological resilience levels and academic grit levels. It is expected that the findings to be obtained from the research will contribute to the studies aimed at increasing the academic achievement of students in mathematics lessons, especially in school environments. The research has some limitations such as being conducted with a limited sample and quantitative approach. Researchers who will deal with this subject in the future may be advised to conduct this study with a higher number of participants and using different variables and approaches.