First Grammar School in Celje is a coeducational nondenominational state secondary general education school for students aged between 15 to 19 in Celje, Slovenia. It was the first high school built in the region, established in 1808 by the Austrian Empire. Initially, the language of instruction was only German, although the great majority of the pupils came from the Slovene Lands.
In 1895, the first classes with Slovene as the language of instruction were established. German nationalists in Austria-Hungary fiercely opposed this move, which resulted in a government crisis and fall of the cabinet of prince Alfred III. zu Windisch-Grätz. After the end of World War I and the formation of the State of Slovenes, Croats and Serbs (later Kingdom of Yugoslavia), the high school switched to Slovene as the language of instruction. During its almost 200-year history, many of its pupils have become prominent individuals.