In inquiry-based science education, there have been gradual shifts in research interests: the nature of scientific method, the debates on the effects of inquiry learning, and, recently, inquiry teaching. However, many in-service programs for inquiry teaching have reported inconsistent results due to the static view of classroom inquiries and due to the partial perspective between individual and collaborative reflections. Thus, by means of a theoretical progress model of collaborative reflection, this qualitative research aims to investigate reflections of four participant teachers before and during a half-year in-service teacher program. The model captures the following four interactions for each individual teacher and among the teacher cohort: belief to practice, practice to belief, stimulation, and reinforcement. The audio-video data and their quantification allowed identification of the teachers' consistent prior beliefs and practices as a multiplicity of inquiry teaching and their interwoven progress during the program. The findings are further discussed in terms of the "implicit development" and the "richer repertoire."