The Trends in International Mathematics and Science Study (TIMSS) is a large-scale international assessment that measures students’ achievement in mathematics and science at the fourth and eighth-grade levels. Coordinated by the International Association for the Evaluation of Educational Achievement (IEA), TIMSS is conducted every four years. The 2023 assessment represented the eighth cycle of TIMSS, collecting data from 64 participating countries. This exploratory study examines the influence of several key factors—gender, home learning resources, experiences of bullying, disruptive classroom behavior, and students’ sense of school belonging—on fourth-grade mathematics achievement in Bosnia and Herzegovina. The research sample included 2,712 students (mean age: 10.2 years; SD = 0.4; 1,388 girls and 1,324 boys). Results showed that home learning resources were the most important predictor of mathematics achievement, emphasizing the essential role that home educational conditions play in student academic outcomes. The observed difference between boys and girls in mathematics scores was minimal. Both bullying and disruptive behavior were found to have a statistically significant negative impact on mathematics performance, whereas the effect of students’ sense of school belonging did not reach statistical significance. Home learning resources proved to be the most decisive variable in forecasting mathematics achievement among fourth-grade students in Bosnia and Herzegovina, reinforcing the value of home-based educational support in fostering academic progress. These results suggest the necessity for educational policies and interventions that ensure fair access to learning resources within the home environment. The paper concludes with a discussion of the implications of these findings and outlines potential avenues for future research and educational practice.