With the increased global awareness of the negative impact of scientific, technological and industrial activities on the environment and copious examples of sustainable practices existing in many an indigenous community, the new South African science curriculum statement has called on science teachers to integrate school science with the Indigenous Knowledge Systems (IKS). In response to this call, this study used an Argumentation-Based course (A-B course) to enhance teachers’ understanding of the Nature of Science (NOS) and IKS and their ability to integrate science and IKS in their classrooms. Nine teachers participated in the course over a six-month period. Using questionnaires and interviews, the teachers’ conceptions of, and awareness about the NOS and IKS were assessed before and after the course. Altogether, five of the teachers were interviewed and three of them completed a delayed questionnaire nearly two years after the course. After participating in the course, the teachers were: 1) more willing to accept IKS as a potentially legitimate aspect of a science curriculum; 2) more able to distinguish between science and IKS; and 3) more aware of the appropriate context to use the scientific or IKS worldview than was the case before the course. Although the teachers were enthusiastic about the value of the course as part of their training at the tertiary level, they were less optimistic about its success at the primary or secondary school level.