This research investigated the effect of science-based professional development for primary school teachers on the teachers' subsequent attitudes towards teaching science. The results found that less than five hours of professional development workshops were capable of increasing the science teaching self-efficacy of all but three participants for at least 11 months after the completion of the workshops. This project showed that the informal education sector could enact positive reforms within science education, but only if the context in which the teachers must operate is taken in to account, and reform efforts adapted accordingly.