Modularity is a key principle for the design of a variety of systems, such as products, software, organisations, and, as of late, services. Service research has adopted the concepts of service modularity and service architecture to identify novel ways for achieving various effects, i.e. efficiently meeting heterogeneous demand. In order to advance research on service modularity, we argue that researchers need to be clear about key concepts, such as a characterisation of service modularity and its related effects. Thus, this paper presents findings from a comprehensive and comparative review of extant measurements of modularity and its related effects in key areas of application of the modularity principle, such as networked organisations, product and software development, and services. By surveying extant knowledge on service modularity vs. other contexts, we develop propositions for future research on service modularity.