Social capital is a collective asset important for individual and population well-being. Individuals who experience homelessness may face barriers in accessing social capital due to health challenges, small social networks, and social exclusion. Data from a 4-year longitudinal study was used to determine if housing stability predicted greater social capital and if this relationship was mediated by social support and psychological integration for a sample of 855 homeless and vulnerably housed participants living in three Canadian cities. Findings showed that housing stability was not associated with trust and linking social capital. However, higher levels of social support and psychological integration had a mediating effect on the association between housing stability and trust and linking social capital. These findings highlight the importance of social support and psychological integration as means of promoting social capital for people who experience homelessness and vulnerable housing. Social interventions for housed individuals with histories of homelessness may be an avenue to foster greater social capital by building relationships with neighbors and connections to community resources and activities.