The implementation of new content and pedagogical standards in science education necessitates intensive, long-term professional development of science teachers. In this paper, we describe the rationale and structure of a comprehensive and intensive professional development program of school-based leaders, namely school chemistry coordinators. The year-long program was designed so that the chemistry teachers who enrolled in the program were able to develop in three interrelated aspects: content knowledge, pedagogical content knowledge, and leadership ability. Several strategies for the development of these aspects were adopted from Loucks-Horsley, Hewson, Love, & Stiles (1998). The evaluation of the program focused on the changes that participating teachers underwent regarding their personal beliefs and their functioning as school chemistry coordinators in their schools.