Older adults are increasingly becoming unhoused. Once homeless, older adults are forced to navigate the transition to housing, an area which requires further research. We conducted a secondary analysis of qualitative research data using the theory of ontological security to explore the question: How do older adults experience trauma across the transition to housing following homelessness? During the analysis, we created a central essence ‘When your entire world is upended you have to learn to live in a new reality’, with three underlying themes: 1) My life got “pulled out from under me” and I am struggling to regain even footing; 2) I see reality clearly, “the system is broken”; and 3) The importance of social connection in rebuilding ontological security. Findings indicate the transition to housing presents an opportunity for older adults to rebuild ontological security, however only when they have access to housing that is good quality, deeply affordable, and accessible.