9. London School of Economics and Political Science
Program size: 461
Program cost: $27, 256
Star professors: Jeffrey Chwieroth, Katerina Delacoura, Christopher Hughes
One of the oldest international-relations departments in the world (as well as one of the largest), the London School of Economics and Political Science's IR department provides a number of master's programs, most based in London. The school also runs a joint program for a master of international studies degree with George Washington University in Washington, D.C.