This article conceptualizes service supply chains according to the Unified Service Theory, which defines services as bidirectional supply chains that have customers both providing resources to and receiving resources from service providers. We establish how eight traditional roles in manufacturing supply chains are assumed by customers in service supply chains. Those service–customer roles include component supplier, labor, design engineer, production manager, product, quality assurance, inventory, and competitor. We describe how these eight roles are manifested in both business-to-consumer and business-to-business service contexts. We confirm the distinctiveness of these eight customer roles through an initial empirical study and show how the roles are manifested across different types of services. We then demonstrate how these distinctive customer roles can form the basis for service supply chain innovation.