We study the productivity of U.S. and other foreign-owned plants in the United Kingdom. Using a new data set that can identify for the first time domestic U.K. MNEs in such a study, we find that U.K. MNEs are less productive than U.S. affiliates, but as productive as non-U.S. foreign affiliates. Exploiting dynamic variation in our data, we find evidence suggesting that this additional U.S. advantage is due to the takeover of already highly productive U.K. plants rather than the sharing of superior firm-specific assets. The study also features a novel approach to TFP calculation.