Services are characterised by the involvement of customers and other interest groups in the innovation process. The aim of this study is to understand how and why, in the service context, tensions and potential conflicts between heterogeneous interest groups unfold during processes of innovation. The empirical field in which the investigation was set is facility services, a type of business-to-business support services. The findings were extracted from a longitudinal, in-depth case study of a Danish, multi-national organisation over 13 years, complemented with an explorative study in the Danish facility service context. The findings suggest that tensions and conflicts between heterogeneous interest groups are an intrinsic element of innovation processes in services, and that emphasising them might actually support a clearer understanding of processes of innovation in services. The outcome of the analysis is a process model, which proposes innovation dialectics as one of the driving mechanisms of innovation in services.