Making transdisciplinarity happen: Phase 0, or before the beginning

Both within science and society, transdisciplinary approaches are increasingly employed to address today's sustainability challenges. Often transdisciplinary research processes are structured in three core phases: a) problem identification and formation of a common research object; b) co-production of solution-oriented and transferable knowledge; c) embedding co-produced knowledge through transdisciplinary reintegration. In all phases of this ideal-typical model, the involvement of non-academic actors is essential to meet the challenges of real-world problems, and of transformative research practices. Despite existing guidance for the core transdisciplinary process, its initiation often remains an uncharted area because of its strong context dependency. Based on a concrete transdisciplinary case study addressing sustainability transformation in Transylvania, we bring together our learned experience with initiating a transdisciplinary process using a research-driven approach. To this end, we introduce the notion of Phase 0, as an initiating phase prior to beginning an ideal-typical transdisciplinary process. Within Phase 0, we propose three empirically and literature informed sub-phases: Sub-Phase 0.1) selecting the case study; Sub-Phase 0.2) understanding the case study context from a transdisciplinary perspective; Sub-Phase 0.3) fostering premises for coming together. We outline the general rationale behind these sub-phases, and we illustrate how we carried out each sub-phase in practice. By deriving cross-cutting lessons from the three sub-phases, we enhance the practice of transdisciplinary sustainability research with the aim to leverage its transformative potential.