Encyclopedia of Nineteenth Century Thought provides essential information on, and a critical interpretation of, nineteenth-century thought and nineteenth-century thinkers. The project takes as its temporal boundary the period 1789 to 1914. Encyclopedia of Nineteenth Century Thought primarily covers social and political thinking, but key entries also survey science, religion, law, art, concepts of modernity, the body and health, and so on, and thereby take into account all of the key developments in the intellectual history of the period. The encyclopedia is alphabetically organized, and consists of:

* principal entries, divided into ideas (4000 words) and persons (2500 words)
* subsidiary entries of 1000 words, which are entirely biographical
* informational entries of 500 words, which are also biographical.