[2][3][4][5] He wrote notable works in all the literary genres, including poetry (The Ballads of Petrica Kerempuh, 1936), theater (Messrs. Glembay, 1929), short stories (The Croatian God Mars, 1922), novels (The Return of Philip Latinowicz, 1932; On the Edge of Reason, 1938), and an intimate diary.

[6] Krleža wrote numerous essays on problems of art, history, politics, literature, philosophy, and military strategy,[7] and was known as one of the great polemicists of the century.

[11] Upon his return to Croatia, he was demoted in the Austro-Hungarian army and sent as a common soldier to the Eastern front in World War I.

[11] In the post-World War I period, Krleža established himself both as a major Modernist writer and politically controversial figure in Yugoslavia, a newly created country which encompassed South Slavic lands of the former Habsburg Empire and the kingdoms of Serbia and Montenegro.

[2] He became a member of the Communist Party of Yugoslavia in 1918, but was expelled in 1939 because of his unorthodox views on art, his opposition to Socialist realism, and his unwillingness to give open support to the Great Purge, after the long polemic now known as "the Conflict on the Literary Left", pursued by Krleža alongside virtually every important writer in the Kingdom of Yugoslavia, in the period between the two World Wars.

After the establishment of the Nazi puppet Independent State of Croatia under Ante Pavelić, Krleža refused to join the Partisans headed by Tito.

Supported by Tito, in 1950 Krleža founded the Yugoslav Institute for Lexicography, holding the position as its head until his death.

[21] Krleža's oeuvre can be divided into the following categories: Although Krleža's lyric poetry is held in high regard, by common critical consensus his greatest poetic work is Balade Petrice Kerempuha (Ballads of Petrica Kerempuh), spanning more than five centuries and centred on the figure of plebeian prophet Petrica Kerempuh, a Croatian Till Eulenspiegel.

[22] Krleža's novelistic oeuvre consists of four works: The Return of Philip Latinowicz, On the Edge of Reason, The Banquet in Blitva, and The Banners.

On the Edge of Reason and The Banquet in Blitva are satires (the latter located in an imaginary Baltic country and called a political poem), saturated with the atmosphere of all-pervasive totalitarianism,[24] while The Banners has been dubbed a "Croatian War and Peace".

It is a multi-volume panoramic view of Croatian (and Central European) society before, during, and after World War I, revolving around the prototypical theme of fathers and sons in conflict.

[28] Krleža's memoirs and diaries include Davni dani ("Olden Days") and Djetinjstvo u Agramu ("Childhood in Zagreb").

Other works include Dnevnici ("Diaries") and the posthumously published Zapisi iz Tržiča ("Notes from Tržič") chronicle multifarious impressions.

Harbors Rich in Ships: Selected Revolutionary Writings (The Glembays, 1928, and other early texts).