Science teaching in primary schools has been of concern for at least the last two decades. Despite the recognition of science as a key learning area, science teaching has a low status in the curriculum, and little effective instruction occurs. Within this context, a new draft science syllabus, which uses constructivism as a referent, was trialled in 60 Queensland schools. Thus, the purpose of this research was to investigate how a professional development program designed to support syllabus implementation, impacts on the teaching of primary science. This support was intensive and involved close collaboration between the researcher and the teacher. As teacher development is a critical component of successful curriculum implementation, a carefully planned professional development program was created drawing upon the principles of constructivism. The professional development program had two parts: (1) workshops, and (2) follow-up support by the researcher. This support was intensive, and involved close collaboration between the researcher and the teacher. It was designed to assist a primary teacher to implement in the classroom, a unit of work based on the draft syllabus. An interpretative methodology was adopted to explore the professional growth of a primary school teacher over a three-month period. Four specific questions guided this study. First, in what ways does a teacher change his professional practice in response to a science curriculum innovation? Second, what changes occur in a teacher's beliefs about science, and the learning and teaching of science in response to a science curriculum innovation? Third, what are the supporting conditions for professional growth during the implementation of a unit of work based on a science curriculum innovation? Fourth, what are a teacher's concerns about the implementation of a unit of work based on a science curriculum innovation? A theoretical framework derived from the literature on teachers' practice and beliefs guided the analysis of data collected for questions one and two. To answer questions three and four, a grounded theory approach was used to identify the supporting conditions for professional growth, and the concerns associated with the implementation of a constructivist-based unit of work. Four conclusions emerged from the study. First, with appropriate professional support, worthwhile changes to the teaching of primary science were found to be possible in a short and medium time frame. Second, it was found that teacher professional growth may be initiated by either a change in practice or a change in beliefs. Third, successful experiences in implementing a curriculum innovation, and a willingness to modify beliefs and practice were found to be major factors in improving the teaching of primary science. Fourth, the provision of adequate support, and time for a teacher to engage with change and change processes, and to adopt new practices and beliefs, were found to be central to the effective implementation of a science curriculum innovation. A major outcome of this study is the development of a model of professional growth in primary science education, which identifies the key issues for syllabus implementation.