Concessioners play an important role in park and protected area management by providing visitor services. Historically, concessioners were criticized for their negative impacts on environmental sustainability. However, due to policy changes, technological advances, and shifting market demands, there is a need to reevaluate the role of concessioners in sustainable destination management in and around parks and protected areas. The purpose of this qualitative case study situated in Grand Teton National Park (GTNP), which was guided by social exchange theory, was to explore U.S. national park concessioners’ influence on sustainable development at the destination level from the perspective of National Park Service (NPS) staff, concessioners, and local community members. Sustainability was examined holistically as a multifaceted construct with integrated socioeconomic, cultural, and environmental dimensions. Twenty-three participants completed semistructured interviews. Researchers identified four thematic categories describing concessioners’ influence on sustainability; motivations and barriers to pursuing sustainability initiatives; and situational factors that facilitated concessioners’ sustainability actions. While participants commented on the negative environmental impacts of concessioners and their operations, these data suggest that concessioners were working individually and collaboratively to promote environmental, socioeconomic, and cultural sustainability in and around GTNP. Some concessioners were even described as leaders, testing and driving the development of innovative sustainability policies and practices. These actions were motivated, in part, by contractual obligations and profit generation. However, concessioners also had strong intangible motivators, such as intrinsic values and a strong sense of community, that drove their positive contributions to sustainability. Based on these data, we recommend that those involved in future theoretical and practical work with concessioners acknowledge the importance of both tangible and intangible motivators when attempting to promote higher levels of sustainability achievement and collaboration. This will become increasingly important as land management agencies continue to embrace strategies beyond the traditional “parks as islands” approach to management. Additionally, future work should explore more specifically the role of policy, conceptualizations of sustainability, and private industry sponsorship in promoting concessioners’ contributions to sustainability, especially in collaborative settings. This work is needed to understand if and how these observations generalize to other contexts.