The rise of global private environmental governance has inspired substantial research assessing whether organizations like the International Organization for Standardization (ISO) and the Forest Stewardship Council (FSC) are legitimate. These organizations address global challenges and help overcome collective action problems, but public opposition can severely curb their effectiveness. Yet, we do not know whether the public supports such organizations and perceives them as legitimate. This article draws on diverse political science literatures to outline why a focus on public opinion is important. The article tests two competing arguments explaining potential opposition toward organizations like the ISO and the FSC: accounts centered on the role of sincere preferences over the legitimate locus of authority and on the influence of domestic elite rhetoric. Results suggest that public opinion is generally positive and that elite rhetoric about a potential democratic deficit rather than simple information about the bodies’ governance structures decreases favorability.