London 2012 Volunteering Strategy was premised on the commitment to use the Games as a way of inspiring a new generation of volunteers and contributing to a lasting volunteering legacy for the UK. Using a critical realist evaluation approach, this chapter examines the processes through which the volunteering legacy can be achieved, for whom, under what circumstances, and over which duration. It concludes that the momentum to build on the enthusiasm of 70,000 volunteers was lost, and the volunteering legacy became declared rather than delivered. This inevitably poses questions about the effectiveness of legacy planning and delivery. The chapter extends the body of knowledge about social legacies of mega sport events and their governance and can be highly beneficial for future bids and host cities.