Progressive Democracy, originally published in 1914 with a fresh edition unveiled in 1997, stands as Croly’s second monumental contribution to the doctrine of progressive ideology. Here, Croly intricately expands upon the foundational ideas he introduced in his earlier masterpiece, The Promise of American Life.

Upton Sinclair’s The Jungle, published in 1906, emerges as a groundbreaking exposé. It vividly unveils the appalling conditions endured by workers in the early 20th-century meat-packing industry. This critical work has become indispensable for both students and historians delving into the Industrial Revolution and labor policy.

In his biography, Herbert Croly of ‘‘The New Republic’’: The Life and Thought of an American Progressive (1985), David W. Levy meticulously examines the life and intellectual journey of Croly, offering a thorough exploration of his contributions to American progressive thought.

Published in 1999, The 1900s by Adam Woog provides a sweeping panorama of the United States' political, economic, and cultural landscape throughout the first decade of the 20th century, from 1900 to 1910.