This paper documents the increasing variance in the distribution of college and university endowments and decomposes the increase into components coming from variations in investment returns, endowment spending rates, and annual giving to build the endowment. By simulating counterfactual endowment distributions from 1992 through 2010 without variation in each element we examine the contribution of each component to the total. We find that in addition to the original 1992 variation in endowment levels which is responsible for the largest portion (61%) of the variation in 2010 endowment sizes, variation across institutions in annual giving to the endowment and rates of return are important sources of the increase corresponding to 27% and 38% of the 2010 variance in endowment levels respectively. In contrast, variations in the endowment spending rate across institutions is a far smaller contributor, making up only 7% of the variance.