Young adults who experience homelessness have high rates of mental disorders, yet low rates of outpatient mental health service use. This mixed methods study examined the intersection of homelessness and mental health in a sample of 54 young adults (ages 18–25) who were hospitalized on a short-term, inpatient psychiatric unit. Nearly half (n=26) reported being homeless in the prior year and more than a quarter were homeless at the time of admission (n=15). Qualitative analyses identified key factors that contributed to both mental health problems and homelessness including disrupted support networks, fragile family relationships, foster care involvement, substance use and traumatic events. Homelessness was both a facilitator and a barrier to successfully accessing mental health services to manage mental health symptoms. Findings highlight the interconnection of homelessness and mental health and their common relationship with additional underlying risk factors. Providers across service settings need to recognize the overlap of client populations and provide integrated, trauma informed care to address housing instability, mental health, and substance use together.