Corruption undermines many outcomes across development sectors, yet little  is known about how social norms drive corruption or undermine anticorruption efforts in sector work. The conservation sector is no exception. The current study examined corruption and social norms related to infrastructure investments and site planning decisions and their subsequent effect on conservation outcomes. The study focused on the Puerto Princesa Subterranean River National Park, one of four protected areas under the United States Agency for International Development (USAID) Sustainable Interventions for Biodiversity, Oceans and Landscapes (SIBOL) project in the Philippines, implemented by RTI International. Based on a site visit, key informant interviews, and extensive document analysis, our findings elucidate  a unique governance structure that enabled project partners to navigate the significant corruption risks present. Direct social norms were not found to be driving corrupt decision making. However, indirect norms played a role by dictating inaction or silence—powerful behaviors—in the face of abuse of entrusted power for personal gain. Our analysis highlights the challenges and importance of having practitioners clearly define and understand what they mean by “corruption” as well as the importance of undertaking a systems analysis that incorporates the influence of social norms on behaviors within that system.