Teaching American History is happy to welcome Separation of Powers to its core document collection on American government. It joins Congress,  American Presidency, Political Parties,  The Judiciary, and  The Supreme Court, and will be followed by Federalism. Together, these volumes will provide a wide-ranging, yet detailed account of the major institutions and ideas that constitute American government. Separation of Powers explores a fundamental but elusive concept that explains how the branches of our government work together to achieve our ends, but remain distinct to protect our freedom. As the editors note in their introduction, no less a student of government than James Madison thought that the concept of the separation of powers raised questions that “puzzle the greatest adepts in political science.”