Perceptions play a significant role in an individual's decision-making. This paper reports on a study that investigated primary school science teachers' perceptions of their school district professional development and its basis and impact on the teacher development process in a large district in the Eastern Cape Province, South Africa. From the findings, teachers had negative perceptions that led to the belief that they were not receiving the support and tools they needed for professional development from their district. The impact of their perceptions was evident in the slow or non-implementation of the district's newly launched curriculum reforms. Thus, the significance of identifying and addressing teachers' perceptions is argued, for they play a critical role in how they learn and in how their perceptions inform the changes they make in their teaching practice. Failure to address teachers' perceptions is likely to result in teachers not benefiting from their professional development programs. (Contains 1 note.)