Over the past 50 years, the service sector has grown in most advanced industrialized economies to be the dominant economic activity. Researchers are working to understand service activities and define scientific concepts and methods of service under an emerging research area called service science. Service is defined as the application of competence and knowledge to create value. Value is realized through interactions and cocreation among service systems. Service systems vary in scope (from individuals to businesses, organizations, governments, and nations) and adapt dynamically and connect to other service systems through value propositions. The service system has been proposed as an abstraction for service science, and yet it is not clear how to characterize a given organization as a service system. In this article, we present a review of literature on service system concepts and define a service system framework developed from the literature that can be used to characterize an organization as a service system. © 2012 Wiley Periodicals, Inc.