This article describes the Herbert C. Kelman Institute's experiences with conflict intervention in violent complex conflicts, in particular in Sri Lanka from 2002 and Israel-Palestine from 2011. Theoretical and methodological reflection on these practical experiences led the development of its own approach: the approach of Interactive Conflict Transformation. Theoretical and praxeological dimensions of this approach are reflected as a dialogical interrelation between critical-normative claims, empirical action research with conflict parties and the interactive construction of creative perspectives for conflict transformation. Above all, two conditions of such a transdisciplinary practice-research are discussed, which became clear in these learning processes: 1. New methodological approaches are needed for exploring the "non-negotiable" in the worldviews, values, interests and needs of the conflict parties. 2. In regard to the accompanying theoretical reflection, a transdisciplinary meta-frame is needed that allows to combine a complex conflict analysis with the construction of solution-oriented perspectives.