To rebuild refugee resettlement capacity, the US government has promoted “co-sponsorship” between Resettlement Agencies (RAs) and volunteer groups. As limited existing research shows mixed outcomes, there is a need to understand how these actors collaborate to shape integration. Drawing on interviews with RA staff, volunteers, and resettled refugees in several states, we show that co-sponsorship positions volunteers as both brokers and objects of integration. Volunteers-as-brokers expand the scope and duration of services. However, vagueness around the brokerage relationship can undermine service quality, and volunteers can also overstep boundaries by asserting normative assumptions about entitlements and behaviors. As objects of integration, volunteers gain deeper knowledge of poverty and the limitations of support systems. They may also adopt aspects of the culture that refugees bring. We advance an understanding of the reach of refugee resettlement as an institution by illustrating how co-sponsorship shapes refugee immigration and the experiences and outlooks of volunteers.