The 12th International Conference on Human Aspects of IT for the Aged Population, ITAP 2026, held as part of the 28th International Conference on Human-Computer Interaction, 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 2026 proceedings published just before the start of the conference. Three volumes (LNCS 16734, 16735 and 16736) of the HCII 2026 proceedings are dedicated to this year?s edition of the ITAP Affiliated Conference focusing on topics related to: Health, Telehealth, and Preventive Care Technologies; Cognitive Well-Being and Assistive Interaction; Social Media, Connectedness and Intelligent Assistants;  Digital Inclusion and Age-Related Perspectives on Technology; Methods, Design, and Participatory Frameworks;  Ageing in Place and Everyday Living Support; Mobility and Navigation Services; AI-Empowered Solutions and Intelligent Assistants.