Ambrazevičius studied literature at University of Lithuania in Kaunas and University of Bonn. From 1927 he lectured on Lithuanian literature and folklore in Kaunas. By the end of the 1930s he got involved in numerous organizations for literature teachers and scientists. His major works include Theory of Literature (Literatūros teorija in 1930), two-volume A History of World Literature (Visoutinė literatūros istorija in 1931-1932), Vaižgantas (in 1936), three-volume New Readings (Naujieji skaitymai), Lithuanian Writers (Lietuvių rašytojai in 1938). He also worked on the editorial staff of national daily Lietuva (Lithuania) and Catholic daily XX amžius (The 20th Century). He would sometimes use pseudonym Servus to write for these newspapers. During World War II he edited an underground periodical Į laisvę (Towards Freedom) which he later revived in Germany and in the United States.