Czech, a clear case of a language having a Standard and a strong central vernacular with intensive shifting between them, offers many points of general interest to sociolinguists. This volume is divided in 5 chapters and opens with a general discussion of language varieties. 'The Two Central Language Formations in Czech' gives a summary description of the Czech central vernacular. This is followed by a chapter on 'The Origin and Opposition of Standard and Common Czech' and in the next chapter code switching between Standard and Common Czech is discussed. The concluding chapter presents starting points for a theoretical description of a national language with intralingual variation and a preliminary formulation of perspectives on the stratification of Czech.