In 1941, he published his first language book, "The Italian Language".
Una immagine che lo ritrae è visibile==Citazioni==Nel libro "The Story of Language" Mario Pei fa notare come i neologismi siano di immenso valore nell'evoluzione di una lingua viva e come gran parte delle parole vengano coniate a partire dai neologismi:Sull'uso dell'Esperanto:==Opere==Oltre alle opere già citate Mario Pei ha pubblicato:Linguistica*"French Precursors of the Chanson de Roland", AMS Press 1949*"The Story of Language", Lippincott 1949*"All About Language", Lippincott 1950*"Liberal arts dictionary in English, French, German and Spanish", Philosophical Library 1952*"Liberal Arts Dictionary" (con Frank Gaynor), Philosophical Library, 1952*"A Dictionary Of Linguistics" (con Frank Gaynor), Philosophical Library, 1954*"Language For Everybody: What It Is And How To Master It", New American Library, 1956*"Getting Along in Italian", Bantam Books, 1958*"One Language for the World", Biblio-Moser, 1958*"Getting Along in Russian", Harper Publishers, 1959*"Getting Along in French" (con John Fisher), Bantam Books, 1961*"109 Most Useful Foreign Phrases for the Traveler", Curtis, 1962*"Voices of Man: The Meaning and Function of Language", Harper & Row, 1962*"The Story of English: A Modern Approach", Premier Books, 1962*"Invitation to Linguistics: A Basic Introduction to the Science of Language", Doubleday, 1965*"Getting Along in German" (con Robert Politzer), Bantam Books, 1965*"Glossary of Linguistic Terminology", Columbia University Press, 1956*"Studies In Romance Philology And Literature", Garnett Publishing, 1956*"Words in Sheeps Clothing", 1969*"Talking Your Way Around the World", Harper-Collins, 1971*"Getting along in Spanish", Bantam Books 1972*"Weasel Words: Saying What You Don't Mean", Harper & Row, 1972*"How To Learn Languages And What Languages To Learn", Harper & Row, 1973*"Families of Words", St Martins Press, 1974*"Dictionary Of Foreign Terms", Delacorte Press, 1975*"What's In A Word?