In an April 1899 speech in Chicago, New York, Governor Theodore Roosevelt spelled out what he saw as the path to “national greatness.” 2 According to Roosevelt, the world posed many dangers for a nation that was starting to come into its own. The United States, Roosevelt argued, must not rest on its laurels and “sit huddled within our own borders.”3 Instead, Roosevelt asserted that the United States must constantly struggle and strive for greatness, expanding its power and infl uence around the globe. Colonial expansion was key to Roosevelt’s vision of national progress, with the men who refused to take up “the responsibilities that confront us in Hawaii, Cuba, Puerto Rico, and the Philippines” constituting a great danger to the nation.4 Roosevelt railed against such “timid” and “lazy” men, as well as “the over-civilized man, who has lost the great fi ghting, masterful virtues.”5 The speech, which was later released under the title “The Strenuous Life,” summed up much of Roosevelt’s vision of the world.6 This vision cast national development in evolutionary terms, with struggle and violence the keys to success. For Roosevelt, violent struggle and colonial expansion was not simply the path the United States should follow in the future; it was also the path that had made the United States great in the fi rst place. Roosevelt had developed his ideas about national development and the greatness of the United States years earlier in his widely read history entitled The Winning of the West. Through the writing of Roosevelt and his younger contemporary, Frederick Jackson Turner, evolutionary thought came to play an important role in the conceptualization of progress and American history at the end of the nineteenth century.