Since the early 1990s, transdisciplinary sustainability research has been conceptualized and implemented as problem-oriented research and learning projects in which actors from outside the university are involved. This thesis has three objectives: The first objective is to investigate how the terms culture, multi-, inter-, and transculturality are conceptualized in the literature on transdisciplinary sustainability research. Second, this thesis analyzes the conceptualization and practical implementations of transdisciplinary research and learning projects with regard to cultural differentiation. And third, conceptual contributions were developed to improve the design of transdisciplinary research and learning projects. Therefore, a literature analysis on conceptualizations of transdisciplinary research and learning projects and qualitative research on two transdisciplinary learning projects has been conducted.

The term culture is used in a variety of ways in the literature on transdisciplinary sustainability research (as research topic, background of participants, mode of cooperation, context, interculturality, or knowledge culture), but not clearly defined and differentiated. Key findings relating to the conceptualization of transdisciplinary research and learning projects are: 1) a strong focus on integration and consensus is preventing an more fundamental work on cultural differences of the participants, 2) the selection of participants is limited through the terminology and methodological concepts, and 3) ideas of symmetry and balance between participants lead to a reproduction of power relations. Key findings related to the implementation of research based learning projects are: 1) a strong focus on process orientation and experimentation within the projects, 2) a tension between openness and control with regard to the cooperation and project design, and 3) multiple negotiations of differences in interactions (such as temporality, responsibility, experience, relevance). The results show that the political implications of the research and major categories of inequality as discussed in social and cultural research (such as race, class,
gender, body) are hardly addressed. Finally, implications of the results for transdisciplinary sustainability research have been discussed with regard to literature from social, cultural, and sustainability research and contributions to the design of transdisciplinary research and learning projects were developed with regard to adequate concepts of culture, an understanding of research designs as processes, the exploration of differences and positions, as well as the importance of unlearning.

The findings have implications for the design of transdisciplinary research and learning projects: concepts of culture should not be understood as separate, but as interlinked. In general, concepts of culture should be more defined and open concepts can prevent problematic implications (stereotypes, racism, culturalization) that can conflict with the goals of transdisciplinary research. Furthermore, differentiations should be approached more consciously (e.g., Who differentiates from whom in which way?). This includes developing a sensitivity towards differentiations and exploring them in the research process. Cultural differentiation bear an important epistemological and transformative potential for transdisciplinary research by reflecting own matters of course and exploring commonalities.