We estimate, for each nonprofit organization (NPO) in a sample of 606 US arts NPOs, whether the NPO's level of fundraising is excessive, insufficient, or neither, relative to the level that maximizes net donations. We find that the effect of a 1% increase in fundraising on net donations varies widely across the arts NPOs in our sample - from an increase in net donations of 8.91% of gross donations to a decrease of 3.82% of gross donations. Of the 100 NPOs in our sample with the highest donations, the estimated effect of a 1% increase in fundraising on net donations varies more narrowly - from an increase in net donations of 0.27% of gross donations to a decrease of 0.32% of gross donations. Of these 100 NPOs, we estimate that only 3 engaged in excessive fundraising, but 83 engaged in insufficient fundraising, and 14 did not engage in excessive or insufficient fundraising.We also provide evidence that reported organizational efficiency does not affect donations to arts NPOs. This finding may be useful to managers and directors of US arts NPOs who believe that organizational efficiency does impact donations and who, therefore, incorporate the effect on efficiency in their decisions to allocate resources across fundraising, administration, and program objectives.