Henry Demarest Lloyd was born in New York City on 1st May, 1847. His father was a minister in the Dutch Reformed Church but in 1860 he left and opened a small bookshop. After graduating from Columbia College in 1867 Lloyd attended Columbia Law School. He then worked as an assistant secretary for the American Free Trade Association. He also joined the Young Men's Municipal Reform Association, which helped to overthrow William Tweed, the mayor of New York.
In 1872 Lloyd joined the Chicago Tribune. He worked as literary editor from 1872-1874. In 1874 he became financial editor of the newspaper. Then, Lloyd became the newspaper's chief editorial writer in 1880. While working for the Chicago Tribune Lloyd published a series of articles exposing corruption in business and politics. These articles caused a scene and Lloyd has been described as America's first investigative journalist.
Over the next few years Lloyd was a part of the campaign to bring an end to child labor and to achieve clemency for the men accused of the Haymarket Bombing. He was also a strong supporter of women's suffrage and the trade union movement. Lloyd became a leading figure in the reform movement and influenced a generation of political activists including John Peter Altgeld, Clarence Darrow, William Dean Howells and John Dewey.