In his legendary novel The Jungle (1905 and 1906), Upton Sinclair included a conspicuous number of Lithuanian words, phrases and surnames. This volume is the first attempt to analyze aspects of Lithuanian linguistic and historical data from The Jungle. Sinclair discovered the Lithuanian language in Chicago and explored it with pleasure. He even confessed to having sang in Lithuanian. If you look for “a Lithuanian linguist” working in field-research conditions in Chicago’s Back of the Yards—there is Upton Sinclair! The book targets Sinclair’s motives for choosing Lithuanian characters, his sources and his work methods in “field-research” conditions in Chicago. Some real-life individuals—Lithuanian name-donors for the protagonists of The Jungle—are presented in this volume. Certain details of the turn-of-the-century Chicago depicted in The Jungle are also revealed—for example, the saloon where the actual Lithuanian wedding feast took place and its owner. This volume is of interest to American literary historians, sociolinguists, language historians, and those interested in the history of Lithuanian immigration to America and the immigrant experience in Chicago.