Increasing concerns over environmental degradation and climate change have precipitated a more substantive emphasis on event sustainability. Events of any size and nature have been recognised as creating strains upon the environment due to the often substantive and/or complex resource demands. For example, in terms of participant/spectator impact, transport and equipment demands, food and energy resource usage, waste, and overall carbon emissions. These concerns sit in tandem with consistent calls for sport events and organisations to ensure greater economic and practical efficiency to ensure their viability. While significant scholarly attention has been afforded to large-scale sport events, environmental impacts of grassroots and smaller-scale events also have notable localised/community impacts and may, similarly, afford platforms for influencing behavioural change vis-à-vis environmental consciousness. Drawing theoretically on Transformative Sustainability Learning, the chapter provides examples from the European Union-based, sport-event volunteering project, PlayGreen, as an experiential learning model that privileges knowledge application toward clear environmental responsibility and social change. This context provides strategies to advance sport event volunteering engagement, enactment, and enablement as a valuable framework to promote sustainability learning and social transformation that may be transferred to other informal event educational settings.