Which countries have the most foreign scientists, and which ones suffer from the worst brain drain? To answer these questions, researchers at the National Bureau of Economic Research, in Massachusetts, conducted a Web-based survey of over 17 000 published scientists in 16 countries. (China wasn’t surveyed: The researchers tried but were unsuccessful in administering the survey to scientists there.) While the United States is, unsurprisingly, a popular destination for scientists from around the world, Switzerland actually has the highest percentage of immigrant scientists. On the other side of the coin, Japan is the most insular country surveyed, exchanging relatively little scientific talent with the rest of the world.