Only a small portion of Americans make campaign donations, yet because ambitious politicians need these resources, this group may be particularly important for shaping political outcomes. We investigate the characteristics and motivations of the donorate using a novel dataset that combines administrative records of two types of political participation, contributing and voting, with a rich set of survey variables. These merged observations allow us to examine differences in demographics, validated voting, and ideology across subgroups of the population and to evaluate the motivations of those who donate. We find that in both parties donors are consistently and notably divergent from non-donors to a larger degree than voters are divergent from non-voters. Of great interest, in both parties donors are more ideologically extreme than other partisans, including primary voters. With respect to why individuals contribute, we show that donors appear responsive to their perception of the stakes in the election. We also present evidence that inferences about donor ideology derived from the candidates donors give to may not closely reflect the within-party policy ideology of those donors. Overall, our results suggest that donations are a way for citizens motivated by the perceived stakes of elections to increase their participation beyond solely turning out.