In inter- and transdisciplinary teams, diverse perspectives on a particular problem must be integrated into shared models of the problem. This process has been identified as a core challenge for socio-environmental synthesis research and education. There is little understanding of how to facilitate knowledge integration across perspectives. We generated new understanding of the process of knowledge integration in socio-environmental synthesis through two intersecting processes. First, we reviewed well-established literature in the cognitive, social, and learning sciences that connects material artifacts, boundary objects, and model-based reasoning. Second, we conducted an organized reflection (our own model-based reasoning) on the literature. Key findings include identifying the importance of combining a collective negotiation process with iterative individual external representations of the problem. The external representations are partial, temporary constructs that function as boundary negotiating objects, and enable the scaffolding of cognitive interactions between participants, an essential part of generating shared, integrative problem models between interdisciplinary team members. We hypothesize that facilitating the co-creation of boundary negotiating objects may provide a path forward for enabling more effective interdisciplinary work and the development of a set of knowledge synthesis skills and competencies for students and researchers. This article provides a first report regarding our research on this topic, with additional research papers forthcoming.