This book constitutes the refereed proceedings of the 15th International Conference on Economics of Grids, Clouds, Systems, and Services, GECON 2018, held in Pisa, Italy, in September 2018. The 21 full papers and 9 short papers presented together with 1 invited talk were carefully reviewed and selected from 40 submissions. This GECON 2018 proceedings was structured in three special sessions on selected topics, namely: IT service ecosystems enabled through emerging digital technologies; machine learning, cognitive systems and data science for system management; and blockchain technologies and economics.