Teachers' professional development through collaborative arrangements has been emphasized in the literature despite the lack of sufficient interest and practice in Turkey. This study proposes a new model of team teaching as an in-service professional development program that draws on the principles of effective continuous professional development (CPD) practices. The new team teaching model is practiced in five phases and contains research, collaboration, and reflection stages with a focus on learner-centered instruction. The research adopted a qualitative approach exploring a case study of three English as a foreign language (EFL) teachers regarding their reflections on the model. The data for the study were obtained from semi-structured interviews and archival records. The findings of the study suggested that the teachers' reflections on the new team teaching model centered on what they did through the phases of team teaching, what they learned thanks to the model, what they thought about the model, and how they felt from the beginning to the end of its implementation. Furthermore, the results revealed a gradual shift from negative to positive views on team teaching by the end of the study.