Supplemental instruction (SI) is one of the academic support programmers in the College of Agriculture, Engineering and Science at the University of KwaZulu-Natal, South Africa. Supplemental instruction is based on the concepts of collaborative peer-learning principles, integrating academic learning and critical thinking skills with module content, ultimately developing higher-order thinking and the desired technical competence. This study explored the relationship between student attendance at SI sessions and their academic performance in their respective modules across two schools; School of Life Sciences (SLS) and School of Mathematics, Statistics and Computer Science (SMSCS). Data were collected from first and second year modules offering SI by these schools during the first semesters of 2016 and 2017. A general trend in SI attendance was seen across the modules with more students attending SI in the beginning of semester, before a test or exam. Overall, the pass rates of SI attendees were higher than that of the non-SI attendees. Importantly, among the regular SI attendees, there was not only a noticeable improvement in the pass rate but also of the academic performance in terms of their average marks. In addition to the number of SI sessions attended, the relative effects of other variables such as ethnicity, gender and matric score were also focused on; SI attendance and matric scores were found to be good predictors of the average marks obtained by the students. The results of this study supports the use of SI as an effective academic support programme in these schools.