Transition of socio-technical systems entail interactions within a system but also between different systems.  As these interactions affect the actors, institutions and knowledge of systems and thus the transition of systems, it is crucial to understand these interactions. Therefore, this work group looks into the different types of interactions and their effects on systems, and on transition. We elaborate a structured approach to analyse interactions based on transition literature and projects. Projects that deal for instance with sector coupling usually do not build their approaches on transitions theory. The main question of the project is therefore: How can interactions and their impact on transformation of socio-technical systems be identified, assessed and analysed?