Solving publicly important issues asks for the development of socio-technical approaches, which demands collaboration between researchers with different perspectives, values, and interests. In these complex interdisciplinary collaborations, the course of communication is of utmost importance, including the moments when people, consciously or not, keep silent. In 2012, an interdisciplinary group of water management engineers and scientists collaborated to explore how the university's separate water management research fields could fit better in today's socio-technical trends. Studying the interactional process revealed that during the collaboration many issues were not said by various parties at various times. Results show that, in particular, engineers and scientists stayed silent to secure group performance, to keep disagreements from surfacing, and manage conflicts of interest in the bargaining process. Although silence served various interactional functions, it also shaped the course of interaction in ways that were not intended, resulting in the development of a latent conflict. It is concluded that the concept of silence adds a relevant dimension to our understanding of interaction among engineers and scientists participating in interdisciplinary collaboration that is currently absent in existing literature on scientific collaboration.@en