This article provides evidence and a rationale based on adaptive governance studies for why creating meaningful youth engagement should be understood in terms of intergenerational dialogue, collaboration, learning, and substantive decision-making in global environmental governance. We have centered our discussion on the International Union for the Conservation of Nature (IUCN), as the largest global conservation organization. Through an organizational ethnography approach, we have demonstrated how generational concerns within the IUCN have been framed in terms of participation, and then present the IUCN Intergenerational Partnership for Sustainability (IPS) as a case study of a grassroots movement that is focused on transforming the IUCN towards being a fully intergenerational global governance system for nature conservation. We have described the development of intergenerational thinking and action within the IUCN, and discussed intergenerational governance as being essential for addressing nature conservation challenges faced by local communities in times of increasing global uncertainty. We conclude by providing recommendations for enhancing intergenerational dialogue and building intergenerational governance structures within global conservation organizations.