Progressivism generally means any political movement that wants to change government for the better. It is the opposite of conservatism. It most often refers to a political movement in the United States in the late 19th and early 20th centuries. In the United States, these people wanted to change politics, which was at that time run by big business and corrupt political machines. Most of the people who believed in the Progressive Movement were part of the middle class. Some of the leaders of the progressive movement were Theodore Roosevelt, Hiram Johnson , William Howard Taft and Robert M. La Follette, Sr..