We are concurrently witnessing two significant shifts: digital devices are becoming ubiquitous, and older people are becoming a very large demographic group. However, despite the recent increase in related CHI publications, older adults continue to be underrepresented in HCI research as well as commercially. Therefore, the overarching aim of this workshop is to increase the momentum for such research within CHI and related fields such as gerontechnology. For this, we plan to continue developing a space to discuss and share principles and strategies to design interactions and evaluate user interfaces (UI) for the ageing population. We thus welcome contributions of proposing improved empirical studies, theories, design and evaluation of UIs for older adults. Building on the success of the last three years' workshops, we aim to grow the community of CHI researchers across borders interested in this topic by fostering a space to exchange results, methods, approaches, and ideas from research on interactive applications in support of older adults that are reflective of international diversity.