This research project aims to advance insight in the impact of team teaching, a collaborative teaching model in which two or more teachers collaborate to a certain extent in the planning, teaching and/or evaluation of a course. Despite its overall attractiveness, both in research and practice, there is scant empirical evidence with convincing data on team teaching’s effectiveness to date. Considering the lacunae in the state-of-the-art and the clear call for evidence formulated by the field, the overall research objective of this project is to map the effects of team teaching on both students and teachers. To accomplish this objective, four research lines (RL) are proposed: (1) a large-scale crosssectional survey study, (2) a video-based observation study, (3) a quasiexperimental study, and (4) an intervention study. These research lines will result in four evidence-based utilization products (UP): (1) a Flemishwide professional learning community, (2) an online knowledge-based platform, (3) a professional development program, and (4) a white paper with policy recommendations on team teaching. On a methodological level, this project clearly distinguishes itself from the current state-ofthe- art by conducting large-scale studies that move beyond perceptions, by including more direct measures and a quasi-experimental study. The current proposal will culminate in pioneering contributions to a more comprehensive theory on team teaching, and elevate empirical research on team teaching to the next level. The proposed utilization products tackle urgent needs formulated by the Flemish educational field in general, and a diverse and large group of already engaged stakeholders in particular. For this research project, a new and complementary expert consortium, consisting of two universities and two universities of applied sciences has been established.