Jonas Jablonskis (Kubilėliai nr Šakiai 1860 – Kaunas 1930) graduated in 1881 with a golden medal from the Marijampolė gymnasium, a training ground for future national activists (Kudirka, Basanavičius), then studied classical philology at the University of Moscow (1881-85), where his professors stimulated his study of Lithuanian. In 1889 Jablonskis obtained a teaching position in Latin and Greek in Mitau/Mintauja (present-day Jelgava, Latvia), where he established and led the <em>Literatiškoji Komisija</em> (Literary Commission), which published the Lithuanian newspapers <em>Varpas</em> (“The bell”) and <em>Ūkininkas</em> (“The farmer”). Suspected of anti-tsarist activity, he was transferred to Reval/Tallinn in 1896, where he taught; here he was engaged in editing the dictionary of Antanas and Jonas Juška. When in 1900 he was found to be in possession of prohibited publications, he was exiled to Pskov until 1903. After having moved to Vilnius (1904), he joined the editorial boards of the newspapers <em>Lietuvos ūkininkas</em> (“The Lithuanian farmer”) and <em>Lietuvos žinios</em> (“Lithuania news”), and founded and directed the <em>Aušra</em> publishing house; his teaching career continued at the gymnasiums of Panevėžys (1906-08), Grodno/Hrodna (1908-12), Veliž (nr Smolensk, 1912-14) and, during the war years, in Voronež (1915-18). When Vilnius came under Polish rule in 1918, he moved to Kaunas. He worked as a professor at the Lithuanian University (1922-26) and died one year after his retirement, in 1930.

Jablonskis contributed greatly to the standardization of written Lithuanian. In <em>Lietuviškos kalbos gramatika</em> (“Lithuanian grammar”, 1901), he laid out the principles of the language, systematized its grammar and coined neologisms. While the usage of earlier Prussia-based linguists (Friedrich Kurschat, August Schleicher) had gravitated towards the Prussian-Lithuanian dialect, Jablonskis successfully promoted the Aukštaitian dialect as the basis for the standard written language by arguing that, closer to people’s speech, it was less contaminated with foreign, especially Slavic, influences. His linguistic and orthographic committee work, his journalistic/editorial editing and his discussions with writers on correct usage also contributed to the standardization of the written language.

Jablonskis also assembled textbooks for schools, and translated literature from contemporary Russian, English and French authors. His major works are <em>Lietuvių kalbos gramatika </em>(“Lithuanian grammar”, 1901); <em>Lietuvių kalbos sintaksė</em> (“Lithuanian syntax”, 1911); <em>Rašomosios kalbos dalykai</em> (“Matters of written language”, 1912); <em>Lietuvių kalbos vadovėlis</em> (“Manual of Lithuanian”, 1925); <em>Linksniai ir prielinksniai</em> (“Cases and prepositions”, 1929).