Public libraries in the United States have begun to partner with social work to address the psychosocial needs observed in patrons that are beyond the training and education of most library staff. This is a new area of inquiry with limited research available. Of the few published studies, the majority focus on staff perceptions of patrons’ needs and surveys of patrons experiencing homelessness about their use of public libraries. The present study is the first to examine and compare staff perception of patrons’ needs, patrons’ self-expressed needs, and the actual use of social work services by patrons within one library system. Comparisons are explored between actual service usage alongside the perception of patrons’ needs as originally reported by both staff and patron groups. Implications for library-based social work practice are discussed.