This paper presents research findings of a longitudinal empirical case study that investigated an innovative Computer Assisted Language Learning (CALL) professional development program for pre-service English as Foreign Language (EFL) teachers. The conceptualization of the program was based on the assumption that pre-service language teachers learn better in situated contexts (Egbert, 2006). Therefore, a key component of the program was the development of school-based research projects, in which the student teachers needed to design, implement, and evaluate technology-enhanced EFL lessons in collaboration with in-service teachers. Data were collected via field notes, video recordings of lessons, academic research reports produced by the pre-service teachers, and in-depth interviews with the pre-service and in-service teachers. Our findings indicate that the field experiences provided professional learning opportunities that supported the student teachers' development as CALL practitioners. The participating pre-service teachers especially emphasized the important role played by school-based experiences in allowing them to use technology in authentic language teaching scenarios and to evaluate the impact of technology on language teaching and learning. The paper concludes with a discussion of important principles and guidelines that should underlie and inform such collaborative efforts and a summary of the implications of the findings for the design of CALL pre-service teacher education programs.