Service Science is a new interdisciplinary approach to the study, design, implementation. and innovation of service systems. However due to the variety in service research, there is no consensus yet about the theoretical foundation of this domain. As a basis for a common understanding of service systems and their interactions, Service Science researchers Spohrer and Kwan proposed the service systems worldview. The ISPAR model was presented as a part of this service systems worldview as a tool for identifying ten possible interaction episodes, i.e., the sequences of activities that are undertaken by two interacting service system entities. In this paper we evaluate the use of the ISPAR model as a process model for service systems. We identify the shortcomings of the ISPAR model and propose possible improvements. This analysis leads to the development of a new service process model which is demonstrated through tree different examples
