Mencken's pungent, iconoclastic criticism and scathing invective, although aimed at all smugly complacent attitudes, was chiefly directed at what he saw as the ignorant, self-righteous, and overly credulous American middle class, members of which he dubbed Boobus americanus. His essays were collected in a series of six volumes, Prejudices (1919-27). In the field of philology he compiled a monumental and lively study, The American Language (1st ed. 1919; 4th ed. 1936; with supplements, 1946, 1948). Among his other works are George Bernard Shaw: His Plays (1905), In Defense of Women (1917), Treatise of the Gods (1930), and the autobiographical trilogy Happy Days, 1880-1892 (1940), Newspaper Days, 1899-1906 (1941), and Heathen Days, 1890-1936 (1943), collected in one volume in 1947. Mencken also fought against the strain of Puritanism in American literature and was an important literary champion of such writers as Theodore Dreiser, Sherwood Anderson, Sinclair Lewis, and Eugene O'Neill. His keen interest in and intelligent appraisal of 20th-century American letters are evident in the posthumously collected essays of H. L. Mencken on American Literature (2002).
See his letters (ed. by G. L. Forgue, 1961) and diary (ed. by C. A. Fecher, 1990); biographies by W. Manchester (1950), C. Angoff (1956), S. Mayfield (1968), C. Bode (1969), F. C. Hobson, Jr. (1994), and T. Teachout (2002); studies by D. C. Stenerson (1971), F. C. Hobson, Jr. (1974), C. Scruggs (1984), and E. A. Martin (1984); A. Bulsterbaum, H. L. Mencken: A Research Guide (1988).