Over six months – September 2019 to March 2020 – ten arts organisations throughout England took part in the World’s Largest Arts Fundraising Experiment. The purpose of the project was to identify ways in which galleries, museums, performing arts companies, and touring venues could improve their private income – by attracting new supporters, by persuading existing supporters to contribute more, and to find new ways of giving. The focus was on philanthropy from individuals, and the lens was the potential to use decision science in fundraising.