This book constitutes the proceedings of the 4th International Conference onHuman Aspects of IT for the Aged Population, ITAP 2018, held as part of the 20th International Conference, HCI International 2018, which took place in Las Vegas, Nevada, in July 2018. The total of 1171 papers and 160 posters included in the 30 HCII 2018 proceedings volumes was carefully reviewed and selected from 4346 submissions. ITAP 2018 includes a total of 84 papers. They were organized in topical sections as follows: Part I: aging and technology acceptance; aging and interaction; intergenerational communication and social participation. Part II: health care technologies and services for the elderly; intelligent environments for aging; and games and entertainment for the elderly.