This book contains the refereed proceedings of the 6th International Conference on Exploring Service Science (IESS), held in Porto, Portugal, in February 2015. Service science constitutes an interdisciplinary approach to systematic innovation in service systems, integrating managerial, social, legal, and engineering aspects to address the theoretical and practical challenges of the service industry and its economy. The 27 full papers accepted for IESS were selected from 69 submissions. The papers consider the topics service innovation, service exploration, service design, IT-based service engineering, and service sustainability.