<p>We explain the challenge of interdisciplinary training as experienced in sustainability science—the knowledge system pursuing desirable trajectories of social-ecological systems. We introduce an approach, supported by a case study of a research project, which uses structured public discussions between established disciplinary investigators to reach sufficient common ground for interdisciplinary research. For initial training seminars, the participants in the discussions supply each other, and explain publicly, a shortlist of the main scientific findings and literature in their disciplines; after this, they discuss consensus-building and disagreement phenomena in scientific practices. After the initial training, additional public discussions on related topics further support the development of a common cross-disciplinary language and mutual trust, and reiterate the motivation for the next steps. We argue that such public training helps reduce the risk of failure in interdisciplinary research, since it includes both perceived expectation and legitimization of new interdisciplinary qualities by the audience. It could also have wider spill-over effects to the practices of decision-making for sustainability and to the spread of interdisciplinarity in academia.</p>