From the #GivingTuesday website:
New York’s 92nd Street Y was the catalyst and incubator for #GivingTuesday, bringing the expertise of 139 years of community-management to the project and providing #GivingTuesday a home. The United Nations Foundation joined as partners, bringing their strategic and communications clout to the project. An amazing team of influencers then offered their ideas, contacts and wisdom to help shape and improve the concept. A powerful list of corporations and non-profits agreed to be founding partners, helping spread the word and committing to their own #GivingTuesday initiatives. Since then, countless organizations, friends and leaders have all added their support and talents to make #GivingTuesday a reality.