Weunpackthedistinctchannelsthatcouldbedrivingtheriseincash:growing international business activity, changing precautionary cash needs, declining foreign corporate tax rates, and lastly, active tax minimization behavior by U.S. corporations. The run-up in corporate cash has roots in each of these channels, but the last two are the dominant causes. We first show that the rise in total cash is due almost exclusively to a rise in foreign cash and then ask whether the factors that explain the level of total cash (precautionary savings or foreign taxes) apply equally to domestic and foreign cash. Here we find that the factors that drive the two decisions are quite distinct. Domestic cash is explained mainly by precautionary savings variables, while taxes explain foreign cash.2 There is very little evidence of precautionary motives explaining foreign cash holdings. Our estimates suggest that 79% of the increase in foreign cash (4.1% of the overall 5.2% increase in the foreign cash to assets ratio) is explained by the reductions in tax rates that firms face on their foreign income over our sample period.