4. Princeton University
Program size: 165
Program cost: $38,620
Star professors: John Ikenberry, Robert Keohane, Anne-Marie Slaughter
The Woodrow Wilson School of Public and International Affairs offers not only offers a top-notch program, it also prides itself on generous fellowship funding to help students offset costs. Students also benefit from its many affiliated programs. For example, the World Politics journal is published by the Princeton Institute for International and Regional Studies.