It is widely understood that learners who are proficient in the language of the test are better able to successfully answer the questions and achieve higher scores. That is, learners perform best in their home languages. However, simply administering tests in learners home language in South Africa, with its high levels of poverty and inequality, will not necessarily lead to improved results. While language proficiency is a contributor to higher performance, there are other factors at play. Using the TIMSS 2019 grade 9 data, we present further insight into the debate around language of instruction.