Large scale habitat loss, unprecedented rates of species extinction, and other biodiversity issues have prompted wildlife conservationists to increasingly apply the “flagship” species concept to guide conservation decision making. Flagships are designated based on their ability to serve a socio-economic role, attracting public attention and financial support to conservation initiatives. Critical to flagships success is selecting an appropriate flagship—one that will be widely supported and will not invoke ill-will among any stakeholders. Thus, determining if the species meets certain pre-established criteria that are known to influence social-psychological processes is a critical step in flagship selection. The river otter (Lontra canadensis) is a widely distributed apex predator and possesses various other socio-ecological traits that make it suitable for a flagship species. However, empirical evidence supporting the use of the river otter as a flagship is lacking. In this dissertation, I study the ability of the river otter to serve as a flagship species in the Greater Yellowstone Ecosystem, one of the largest intact temperate-zone ecosystems in the world. I examine visitor attitudes and perceived resource conflicts with river otters and anglers, assess visitor willingness to engage in pro-conservation behaviors to help river otter conservation, and estimate probability of viewing the river otter using camera-traps along the Snake River. In addition to fulfilling certain recommended criteria of a flagship species, such as having a large body size, being charismatic, encompassing a wide-spread geographic range, and being uncommon across the landscape, my results suggest that visitors and anglers have positive attitudes towards the river otter, and that exposure to the river otter increases people’s willingness to engage in pro-conservation behaviors to help conserve the river otter and its aquatic habitat. However, pre-existing negative media portrayals as well as low visibility of the species, are potential liabilities of the river otter as a conservation flagship. The studies in this dissertation deepen the understanding of river otter socio-ecology as well as develop and apply elements of a socio-ecological framework that refine the approach of effectively selecting a successful conservation flagship.