• Unique rapid ethnographic study of low-threshold supervised consumption services.
• Examines involvement of people who use drugs as staff in these services.
• Describes how this approach enhanced intervention effectiveness.
• Provides unique findings regarding benefits and challenges for staff.
• Highlights the need for additional funding and resources to support this approach.
Overdose prevention sites (OPS) are a form of supervised consumption facility that have been implemented in Vancouver, Canada as an innovative response to an ongoing overdose epidemic. OPS are primarily staffed by peers – people who use(d) drugs (PWUD) – trained in overdose response. We sought to characterize peer worker involvement in OPS programming, including how this shapes service dynamics and health outcomes among PWUD. Data were drawn from a rapid ethnographic study examining the implementation, operations and impacts of OPS in Vancouver from December 2016 to April 2017. We conducted approximately 185 h of observational fieldwork at OPS and 72 in-depth qualitative interviews with PWUD. Data were analyzed thematically, with a focus on peer worker involvement at OPS and related outcomes. OPS implementation and operations depended on peer worker involvement and thus allowed for recognition of capacities developed through roles that peers were already undertaking through local programming for PWUD. Peer involvement at OPS enhanced feelings of comfort and facilitated engagement with OPS among PWUD. These dynamics and appreciation of peer worker expertise enabled communication with staff in ways that fostered harm reduction practices and promoted health benefits. However, many peer workers received minimal financial compensation and experienced considerable grief due to the emotional toll of the epidemic and lack of supports, which contributed to staff burnout. Our findings illustrate the specific contributions of task shifting OPS service delivery to peer workers, including how this can enhance service engagement and promote the reduction of harms among PWUD. Amidst an ongoing overdose epidemic, expanding formalized peer worker involvement in supervised consumption programming may help to mitigate overdose-related harms, particularly in settings where peers are actively involved in existing programming. However, efforts are needed to ensure that peer workers receive adequate financial support and workplace benefits to promote the sustainability of this approach.