The International Conference on Cloud Computing and Services Science (CLOSER 2026) is a conference focused on the highly important area of Cloud Computing, considering its infrastructure, operations, and services through the global network, with a strong link to Services Science. The conference is not limited to the union of these two fields, but rather explores how Services Science can provide theory, methods, and techniques to design, analyze, manage, market, and study various aspects of Cloud Computing. The event is organized by INSTICC and will be held in conjunction with other conferences, including CSEDU 2026, GISTAM 2026, ICT4AWE 2026, VEHITS 2026, IoTBDS 2026, SMARTGREENS 2026, and IMPROVE 2026. The conference targets a broad audience, including researchers, practitioners, and professionals in the field of Cloud Computing and Services Science. The program will feature keynote lectures by Sara Bouchenak, Rajiv Ranjan, and Vasilios Andrikopoulos, and a short list of best papers will be invited for a post-conference special issue of the Springer Nature Computer Science Journal. The conference will also feature a book publication with Springer in the CCIS Series, with proceedings submitted for evaluation for indexing by Web of Science/Conference Proceedings Citation Index. The conference areas include Cloud Computing Paradigms and Practices, Cloud AI, Cloud Security and Privacy, Cloud Computing Enabling Technology, and Services, Platforms, and Applications. The conference will be held in a hybrid format, allowing speakers to present remotely if unable to travel to the venue. Registration to CLOSER 2026 allows free access to the other co-located conferences, except for speakers who are allowed to present remotely.