This research is an analysis of the performance of the South African pupils on the Third International Mathematics and Science Study-Repeat (TIMSS- R) in which pupils wrote tests in mathematics and science, but in South Africa pupils also had to write an English test as a national option. The research reported here concentrates on the final outcomes of the exploration of the performance of the South Africa pupils in mathematics and the relationship between mathematics achievement and proficiency in English. The factors relating to the performance in mathematics and English language proficiency were explored. Results of mathematics tests; results of the English language tests; and contextual factors on students, classroom, and school are reported. This research shows that in South Africa, pupils tended to achieve higher scores in mathematics when their language proficiency in English was higher.