On the basis of a ‘language biography’ of Bedřich Smetana, determined by use of Czech and German, this article reconstructs his use of Czech as preserved in his formal and informal correspondence and evaluates it in relation to grammar books and dictionaries of his time. The ‘language biography’ also takes into account the legal and de facto position of Czech in the Czech lands and in particular the places where Smetana lived with his family. Smetana’s spelling, morphology, and other aspects of his writing in Czech show both direct and indirect influences from German, reflecting his lack of a formal education in Czech. Not uncommonly his writing is oriented toward spoken, non-standard forms; in spelling as well as in vocabulary he sometimes ‘borrowed’ directly from German, and we can find semantic ‘borrowings’ as well. In morphology, whose written form Smetana consciously tried to master as an adult, we sometimes find clear errors in his writing. Nevertheless, Smetana may be considered a bilingual user of both Czech and German, who was in his adult age capable of suitable expression in relevant spheres of discussion in both languages although his written Czech shows certain peculiarities determined by a Czech education during his youth.