The goal of this paper is to assess whether innovation in services can be described as a coherent and steady system. Our results are based on a survey of a great deal of theoretical but mostly empirical literature, including a European project called SI4S (Innovation in services and services in innovation). We first present some general characteristics of services and of service innovations. Then, we analyse some typical innovation patterns in services. These patterns are different versions or configurations of a model of actors and trajectories. The discussion of these different patterns leads us to the conclusion that innovation in services is not an institutionalised system but rather a loosely coupled system.