Jagić was born in Varaždin (then known by its German name of "Warasdin"), where he attended the elementary school and is the place where he started his secondary-school education. He finished that level of education at the Gymnasium in Zagreb. Having a particular interest in philology, he moved to Vienna, where he was lectured in Slavic studies under the guidance of Franz Miklosich. He continued his studies and defended his doctoral dissertation "Das Leben der Wurzel 'dê in Croatischen Sprachen" in Leipzig (Germany) in 1871.