Policymakers and managers are promoting Rangeland Fire Protection Associations (RFPA) as one way to better incorporate private citizens as active participants who contribute to fire suppression efforts on public rangelands. While the RFPA program is growing in popularity, little is known about the way that RFPAs establish and operate. This is especially true in mosaic management scenarios characterized by fragmented landownerships and a variety of land or fire management entities responsible for wildfire suppression. Our goal was to investigate how an RFPA forms and functions in a management scenario characterized by: 1) proximity to exurban residential development; 2) agreements with multiple local, state, and federal wildfire suppression entities; and 3) a geographically disperse protection district. We conducted in-depth interviews with RFPA members, land or fire management professionals, emergency managers, and local interest groups who interact with the Black Canyon RFPA (BCRFPA) in southwestern Idaho. We found that the BCRFPA leveraged the insights, documents and support of existing RFPAs during their establishment, but ultimately had to adapt the RFPA idea to specific elements of their local context. Members of nearby rural fire districts were initially apprehensive about the formation of the BCRFPA due to concerns about resource competition (e.g., funding and large equipment). RFPA members with professional firefighting experience helped alleviate those tensions by explaining how the RFPA would integrate into existing wildfire management networks. The BCRFPA provided local knowledge about road conditions, water resources, and fuel conditions and initial attack to fill in gaps in landscape-level wildfire protection. However, the proximity of residential areas to the BCRFPA protection district made decisions about fire suppression more complex by introducing trade-offs between residential and rangeland resource protections. Ultimately, our results indicate that RFPAs can help rangeland human populations better adapt to wildfire risk, but that social fragmentation may challenge RFPA functioning.