Giving circles and other forms of collective giving (hereafter referred to as GCs) have grown significantly in visibility and popularity over the past 15 years. Often started by donors, they are widely understood to be highly flexible, democratic, do-it-yourself vehicles for giving. Previous research has illuminated the positive impact that participation has on the giving and civic engagement of donors. Until recently, however, our understanding of the scope and scale of GCs was 10 years out of date! This research presents an updated understanding of the current landscape of GCs and similar models of collective giving or giving collaboratives in the United States. This research comprises the first of a three-part inquiry, which also looks at research underway related to the impact of participation in GCs on donor giving and civic engagement, and a study of the relationships between GCs and their hosting organizations.