Schools globally are characterised by an increasingly diverse learner population in terms of age, gender, language, socio-economic background, cultural practices and learning abilities. The diverse needs of learners in schools have implications for teacher training, as it demands a shift from the traditional “one-size-fits-all” approach to a more inclusive approach. Because teachers play a significant role in addressing diversity among all learners, several teacher-training programmes have been implemented worldwide since the inception of inclusive education. The main purpose of these programmes is to ensure that teachers acquire the relevant knowledge and skills to meet the learning needs of all learners in schools. One of these skills pertains to curriculum differentiation for making the curriculum accessible to all learners irrespective of their abilities. This research investigation was rooted in Bronfenbrenner’s ecological model. Situated in the interpretative paradigm, the study adopted a qualitative approach. A multiple case study research design was employed to investigate nine Foundation Phase teachers from rural, township, and former Model C full-service schools. All of them had completed the BEd (Hons) in Learning Support programme at one of South Africa’s major universities. Semi-structured face-to-face individual interviews were conducted, and a document analysis was used to explore participants’ understanding and implementation of curriculum differentiation. The analysis of the study revealed that teachers who had completed the BEd (Hons) in Learning Support programme had the necessary theoretical knowledge of the concept of curriculum differentiation. However, most of them faced difficulties regarding the understanding and implementation of curriculum differentiation. The study also showed that teachers did not make use of official documents that guide and explain the differentiation of school curriculum to meet the diverse needs of learners in full-service schools. In the light of these findings, five sets of recommendations were made in ensuring the effective implementation of curriculum differentiation in schools in order to make the curriculum accessible to all learners.