The wealthiest 10% of donors now give 90% of charitable dollars in the U.S., but little is known about what motivates them. This study uses a natural field experiment, tracking over five thousand high capacity donors, to lend preliminary insights into the world of high capacity givers. On some dimensions, high capacity donors mirror modal donors: there is persistence in giving patterns, signals of program quality influence giving, and the price of giving is not unduly important. Unlike typical small donors, the givers in our data respond only on the intensive margin, and often with a longer time lag. Our study highlights the value to practitioners of partnering with academics, as our intervention has generated $30 million in incremental donations to the University.