As teachers' knowledge determines to a large extent how they respond to educational innovation, it is necessary for innovators to take this knowledge into account when implementing educational changes. This study aimed at identifying patterns in the content and the structure of science teachers' knowledge, at a point in time when they still had little experience in teaching a new subject, that is, Public Understanding of Science. We investigated three domains of teacher knowledge: Teachers' pedagogical content knowledge (PCK), subject-matter knowledge, and general pedagogical knowledge. A semi-structured interview and a questionnaire were used. From the analysis of the data, two types of teacher knowledge emerged. One of the types was more integrated and more extended in terms of PCK. Teachers who represented this type of knowledge had developed PCK that connected the various programme domains of the new science subject. In both types, PCK was found to be consistent with general pedagogical knowledge. In both types, however, subject-matter knowledge was similar, and not directly related to the other knowledge domains. Implications for the implementation of the new subject are discussed.