The 18th International Conference on Social Computing and Social Media, SCSM 2026, held as part of the 28th International Conference, HCI International 2026 (HCII 2026), took place in Montreal, QC, Canada during July 2026.A total of 7435 individuals from academia, research institutes, industry, and government agencies from 94 countries submitted contributions to HCII 2026. Following peer review, 1463 papers and 360 posters (as short research papers) are included in the volumes of the HCII proceedings published just before the start of the conference.Two volumes (LNCS 16715 and 16716) of the HCII 2026 proceedings are dedicated to this year’s edition of the SCSM Conference focusing on topics related to:• Social Computing and Social Media (Part I): User Experience and Behavior in Social Media; AI in Social Media; and Information, Misinformation, Privacy and Trust• Social Computing and Social Media (Part II): Consumers and Streamers in Social Media; Social Media, AI and Learning; and Health Communities
