Sponsorship: NERC RONO: NE/I004351/1There is emerging agreement that sustainability challenges require new ways of knowledge production and decision-making. One key aspect of sustainability science, therefore, is the involvement of actors from outside academia into the research process in order to integrate the best available knowledge, reconcile values and preferences, as well as create ownership for problems and solution options. Transdisciplinary, community-based, interactive, or participatory research approaches are often suggested as appropriate means to meet both the requirements posed by real-world problems as well as the goals of sustainability science as a transformational scientific field. Dispersed literature on these approaches and a variety of empirical projects applying them make it difficult for interested researchers and practitioners to review and become familiar with key components and design principles of how to do transdisciplinary sustainability research. Starting from a conceptual model of an ideal-typical transdisciplinary research process, this article synthesizes and structures such a set of principles from various strands of the literature and empirical experiences. We then elaborate on them, looking at challenges and some coping strategies as experienced in transdisciplinary sustainability projects in Europe, North America, South America, Africa, and Asia. The article concludes with future research needed in order to further enhance the practice of transdisciplinary sustainability research.Peer reviewe

Transitions towards sustainability are urgently needed to address the interconnected challenges of economic development, ecological integrity, and social justice, from local to global scales. Around the world, collaborative science-society initiatives are forming to conduct experiments in support of sustainability transitions. Such experiments, if carefully designed, provide significant learning opportunities for making progress on transition efforts. Yet, there is no broadly applicable evaluative scheme available to capture this critical information across a large number of cases, and to guide the design of transition experiments. To address this gap, the article develops such a scheme, in a tentative form, drawing on evaluative research and sustainability transitions scholarship, alongside insights from empirical cases. We critically discuss the scheme's key features of being generic, comprehensive, operational, and formative. Furthermore, we invite scholars and practitioners to apply, reflect and further develop the proposed tentative scheme -making evaluation and experiments objects of learning.

Purpose -This paper aims at presenting the theoretical concepts of the transdisciplinary case study approach (TCS), which is a research and teaching approach developed and elaborated at the Swiss Federal Institute of Technology (ETH), as a means of transition support. Design/methodology/approach -The paper reveals the historical roots of case studies, transdisciplinarity and sustainable development as teaching and research paradigms. The TCS approach is presented, which has been developed at ETH for supporting transition management of regional, urban, and organizational systems. This approach is entrenched by an ontology that reveals the basic characteristics of ill-defined transition problems, an epistemology that refers to Probabilistic Functionalism and distinguishes between multi-layered systemic and normative epistemics, a methodology that includes a set of methods for case representation (including modelling and projection), assessment, and strategy building, and a project management model that refers to more than a dozen TCSs in the field of sustainable development. Problems of validity of TCSs as a research methodology are discussed. Findings -Three major strengths of the TCS approach presented in the paper are: that it is based on three sound paradigms, which focus on different, relevant characteristics of complex, human-environment systems; i.e. the case study approach, transdisciplinarity and sustainable development, that it is strictly organized according to an elaborated and consistent theoretical framework that includes ontological, epistemological, methodological, and organizational considerations, and that it is itself subject to an ongoing inquiry and adaptation process. All theoretical considerations of the paper are clarified be elaborated examples from the more than 10 years experience with TCS of the authors. Practical implications -The paper gives a comprehensive overview of the theoretical foundation of TCS that might assist other scientists engaged in case study research and teaching to further develop their approaches. Additionally, relevant topics for further research in the field of TCS are presented which hopefully induce an inspiring discussion among case study researchers. Originality/value -As far we know, this paper is one of the first that presents a comprehensive and theoretically sound overview of applying transdisciplinary case studies as means of sustainability learning. Thus, it can be seen as a first, crucial step for establishing the new research field of TCS The current issue and full text archive of this journal is available at research and a sound research community of complex, transdisciplinary problem solving towards sustainability learning.

Purpose -The purpose of this paper is to present the transdisciplinary case study (TCS) as a learning framework based on what we call functional socio-cultural constructivism and project-based learning (PBL). In doing so, the paper attempts to illustrate the applicability of TCS to learn competencies and skills necessary to research problems of sustainable development. Design/methodology/approach -TCS is considered a learning framework based on the principle of self-regulated learning; i.e. students must actively deal with the requirements as well as plan and execute their project work within their own worldviews and goals. TCS methods are essential as we tackle complex real-world problems. Findings -The paper discusses challenges and obstacles of such an approach and present lessons learned since 1994, on both the viewpoints of students and of teachers. It conclude that case study learning is a demanding task, especially in a transdisciplinary context where more challenges emerge than in PBL, since goals of teachers, case agents, and students have to be balanced. Practical implications -TCS or courses like it are important for universities at the present time. Under present budget restrictions and a wide-ranging mistrust of society toward universities, there is a necessity for a new contract between society and research: students should learn to take over responsibility in societal contexts and be able to communicate beyond the "ivory tower". Originality/value -The learning goals of TCS differ from the goals of most university courses. They are more comprehensive and include complex problem solving, societal context, and group processes. The ambitious goal is that students become enabled to tackle complex, real-world problems.

The involvement of stakeholders and the public in societal decision processes has lately received increased attention. We suggest that appropriate and tailored techniques should be selected and integrated to provide the prerequisites for inclusive involvement depending on the issue, type, goals and phase of the decision process in question, i.e. an analytic, systematic and dynamic approach to collaboration. In a transdisciplinary case study design we integrate diverse analytical methods whereby a process of mutual learning between science and people from outside academia is strived for. Our framework for collaboration is illustrated by a case study on sustainable landscape development in the Swiss prealpine region of Appenzell Ausserrhoden.Keywords Societal decision process Á Involvement of stakeholders and the public Á Collaboration Á Transdisciplinary case study design Á Sustainable development