Marketing theory and practice both recognize the increasing importance of customer collaboration for service provision and innovation. As part of such customer collaboration, customers of electronic services coproduce knowledge in varying degrees. An evolving phenomenon, knowledge coproduction has yet to receive much research attention; we therefore conduct a qualitative study of the roles customers play in knowledge coproduction and their resultant influence on different innovation tasks from a service provider view. Data from three electronic service interaction channels, involving managers, engineers, and customers; case study findings; and an extensive literature review indicate the importance of knowledge coproduction by customers and its ability to improve different tasks substantially during innovation activities. The results show three different roles of customers in knowledge coproduction and explain comprehensively how each role impacts various innovation tasks.