The present study investigated the effects of a pre-service teaching program on changes in student teachers' pedagogical knowledge. Twelve student teachers drew a concept map on "effective teaching" on four separate occasions at two designated points each before and after field teaching during a period of eight months. Five in-service teachers were also recruited to draw the map. The results showed a developmental trajectory of pedagogical knowledge in this particular group of student teachers during the period in which they received the training program. Their pedagogical knowledge appeared to be enriched and more connected during the time they were taking the required courses and participating in the field teaching sessions. However, their enhanced knowledge appeared to involve more detailed elaboration of the existing constructs appearing in the previous maps rather than those of structural reorganization of pedagogical knowledge. Experience gained in the guided field teaching helped make these aspects salient for the student teachers that are more directly related to classroom teaching. This has the potential as a precursor to the declarative-to-procedural knowledge transformation in student teachers' learning to teach. The results suggest some important issues to be considered for improving quality of teacher training programs.