This book constitutes the refereed proceedings of the 17th International Conference on Web Engineering, ICWE 2017, held in Rome, Italy, in June 2017. The 20 full research papers and 12 short papers presented together with 6 application papers, 6 demonstration papers, and 6 contributions to the PhD Symposium, were carefully reviewed and selected from 139 submissions. The papers cover research areas such as Web application modeling and engineering, human computation and crowdsourcing applications, Web applications composition and mashup, Social Web applications, Semantic Web applications, Web of Things applications, and big data.