Using data from the Trends in International Mathematics and Science Study (TIMSS), this study examines the student and school characteristics that contribute to students' mathematics performance in early elementary school in Chile. Previous research has separately analyzed the association of student and school factors with mathematics performance. This study uses multilevel modeling analyses to account for those factors together and understand variability within and between schools. The sample in this study was 6,322 fourth grade students from 169 schools. The students' mean age was 10.07 (SD = 0.50); 49.6% were girls. The results from this study show that student characteristics, such as the home mathematics environment, helped explain the variation between schools more than within schools. These findings highlight the importance of considering contextual factors, such as parent-child math interactions, when developing education policy and intervention to foster students' mathematics skills.