PRISM (Projet Réaffiliation Itinérance Santé Mentale-mental health and homelessness reaffiliation project), is a new shelter-based mental health service in Montreal, Canada. It offers short-term residential services in a shelter with the aim of housing and connecting the person to the appropriate services in the community. This qualitative research project was designed to gain a rich understanding of service-user experience within this program, and to apply these impressions to a broader reflection concerning how to best serve the needs of homeless people living with severe mental illness. We conducted in-depth interviews with 20 clients from the all-male PRISM-Welcome Hall Mission at program intake and departure between May 2018 and March 2019. We used methods stemming from grounded theory to analyze themes emerging from the interviews. Analysis revealed three core aspects endorsed by PRISM clients as helpful to their recovery: first, the community-based and flexible PRISM structure allows for continuity in daily routine through the preservation and expansion of the client's existing informal resource network; second, the secure environment is conducive to improving one's physical and mental health; and third, the multimodal mental health and social service approach used at PRISM is appreciated and stands in contrast to what most have experienced during other inpatient experiences. This led us to reflect more broadly on the benefits of a shelter-based intervention, as a catalyst to the achievement of longer-term goals such as housing, as well as flexible care adapted to the specific needs of these individuals. Even though this study took place in a specific program in Quebec, it sheds light more broadly on how to best meet the needs of individuals with mental illness living in homeless situations and contributes to the growing literature on men's mental health.