In literary criticism, naturalism is a word sometimes used loosely as a synonym for realism, and also in reference to works which show a pronounced interest in, sympathy with and love of natural beauty. Properly speaking, it should be used to describe works of literature which use realistic methods and subjects to convey a philosophical form of naturalism; that is, a belief that everything that exists is a part of nature and can be explained by natural and material causes, and not by supernatural, spiritual or paranormal causes.

In literature naturalism developed out of realism. The main influences that went to forming a different point of view were Darwin’s biological theories, Comte’s application of scientific ideas to the study of society, and Taine’s application of deterministic theories to literature. The Goncourt brothers appear to have been the first to establish the naturalistic point of view in literature in Germinie Lacerteux (1865), whose analytical investigation of the rather squalid life was much appreciated by Emile Zola, the high priest of the naturalistic movement in literature. Zola’s influence has been very considerable and is discernible in many plays and novels of the last hundred years. He made his most great impact in Germany, and then later to the other side of the Atlantic. Notable writes are Theodore Dreiser, Frank Norris and Stephen Crane.