Abstract: Background: The inclusion of people with lived and living experience of substance use is essential to effective and client-centered harm reduction services and strategies. The aim of this study is to critically examine and characterize peer worker roles and the definition, recognition, and support for these roles within harm reduction organizations. Methods: Fifteen interviews were conducted with peer workers—people with lived and living experience of substance use engaged in harm reduction service delivery—in British Columbia, Canada. An interpretive descriptive approach to data analysis was used to generate themes that best illustrated the roles of peer workers. Findings: Two interrelated and overarching themes are presented: (1) peer work in practice; (2) organizational support. Our findings illustrate that peer work is incredibly complex and demanding, requiring peers to be at the forefront of support within their communities while simultaneously navigating the oppressive structures within which they work. While peer workers found a high degree of purpose and meaning in their day-to-day work, their roles lacked definition within organizations, which produced feelings of ineffectiveness and being undervalued. A lack of organizational understanding and recognition of their roles was evident from unclear "peer" role titles, a lack of role communication and expectations, the representation of experiential knowledge, and a lack of role support and training. Conclusions: These findings may help harm reduction organizations understand peer work and worker roles which may inform and promote equity in future harm reduction initiatives that include people with living and lived experience of substance use.