In recent years, numerous approaches and concepts have been developed that can be seen as forms of a new marketing paradigm. In this context, the construct of relationships has been emphasized as a central guiding principle of marketing thought. The goal is to transform the challenges arising from changes in the environment into sustainable competitive advantages. However, the potential of consistent relationship management has not yet been fully realized. Jan Daniel examines the vertical inter-firm collaboration between manufacturers and suppliers in companies in Germany. The focus is on questions of identification, definition, and operationalization of relevant factors in relationship management. Additionally, he analyzes internal and external influencing factors on the quality and intensity of inter-firm collaboration.