The approach to science education known as Science, Technology and Society (STS) has recently been widely adopted. An STS school-based project, initiated by a pilot group of teachers and two science-educational researchers, served as a case study for this paper. This collaborative group was responsible for the planning and implementation of an inservice course for science and technology teachers, that aimed to develop an STS rationale. Teachers conceptual change, the process of constructing their STS content and pedagogical knowledge, is explored in terms of our model of conceptual change. Finally, we suggest that STS should be viewed as a learning orientation rather than as a specific content or subject matter.