Pedagogical content knowledge (PCK) is essential to career development for teachers. Teachers can develop their own PCK by research-based activities such as action research and lesson study, with a particular emphasis on the employment of classroom practice, information technology, and collaborative learning. However, in recent studies, most of the models for enhancing teachers' PCK focus on individual teachers or teacher groups, and there is less chance of receiving support from the school leadership and institutional resources. This study proposes a development model for PCK known as the 3C-model and implements a support system for it, known as EDUPLAN. The model engages teachers in collaboratively constructing and sharing a knowledge-base of lesson plans with the involvement of different levels of school members for their school's curriculum. Through the process of school-based curriculum development, the model was found to increase teacher PCK and collaboration. Finally, the supporting system is found to be capable of enhancing performance in lesson plan construction and revision and thus the efficiency of PCK development. (Contains 4 tables and 11 figures.)