In the field of labor relations, there exists a multitude of institutions and actors that are more or less closely intertwined in practice. Social science research has generated diverse insights over the past decades into the structures, working methods, and influence opportunities of individual actors and institutions representing interests. However, the network of relationships between the different levels and areas of action, as well as their interactions, has been comparatively under-researched. Against this background, the edited volume focuses on the interface problems and interactions between different institutions and levels within the multi-level system of labor relations. This is approached from various perspectives: from the connection between works councils and trade unions at the company level to the complete.