EN
Last two decades of the 19th century were also a peak period of the Czech immigration to Vienna. The study analyzes reasons why most of tens of thousands immigrants from Czech speaking parts of Bohemian lands were not recorded during population censuses 1880–1910 with the Czech language of common communication. For this reason it first brings forth a situation of the Czech minority and a social climate it had to face in Vienna and then it defines a category of the “language of common communication” used in pre-Cisleithan censuses. Later on it describes a course of the census of the language of the common communication in Vienna. It also takes into account interest positions of the Cisleithan state (a support of a natural migrant assimilation out of the reason of social cohesion sustenance), German nationalistic activists (an assimilation of Slavic immigrants in the German territory “at any rate”, that is also a violent one) and also of Czech nationalistic activists (the fight against assimilation and a denial of a natural assimilation existence).