KIBS firms are business-to-business service firms that often design their services to satisfy specific clients’ needs and for which clients become co-producers of innovative solutions. Along with clients, other partners often support KIBS firms’ innovation processes. This chapter describes the interplay between service customization and clients’ collaboration and the way in which KIBS firms spur innovation processes in clients’ firms as well as the relevance of the broader network of KIBS firms’ partners in supporting innovation in KIBS.