© The Authors 2015. Published by Oxford University Press on behalf of the European Finance Association. All rights reserved. This article examines whether foreign investor heterogeneity plays a role in stock liquidity in a sample of 27,828 firms from thirty-nine countries worldwide. Foreign direct ownership is negatively associated with stock liquidity, while foreign portfolio ownership is positively associated with stock liquidity. Consistent with theoretical predictions, foreign ownership explains stock liquidity through both trading activity and information channels. The value-enhancing benefits of foreign direct investors' monitoring efforts outweigh their liquidity costs and high adverse selection premium. However, the positive impact of foreign portfolio ownership on firm performance becomes negative and is not robustly significant after controlling for liquidity.