We study charitable giving within social groups. Exploiting a unique dataset, we establish three key relationships between social group size and fundraising outcomes: (i) a positive relationship between group size and the total number of donations; (ii) a negative relationship between group size...

Decisions to donate time or money for charitable purposes are typically seen as make-or-buy decisions, implying that there should be a clear distinction between individuals engaging in one of these two forms of giving and that this distinction should be somehow linked to opportunity costs. But...