Merriam joined the faculty at the University of Chicago in 1900 as the first member of the political science faculty. He authored "A History of American Political Theories" in 1903, a notable analysis of American political movements which strongly supported the emerging Progressive movement. He moved up quickly in the department, reached the rank of full Professor in 1911, and served as chairman of the department of political science from 1911 until his retirement. From 1907 to 1911, he served as chairman of the College of Commerce and Administration (the precursor to the Booth School of Business).