Demographics of the Kingdom of Yugoslavia

The Kingdom of Yugoslavia existed between its creation in 1918 until its occupation and partition by Axis powers in World War II. The first census in 1921 enumerated 11,984,911, while the second and last census in 1931 enumerated 13,934,038 people. While both censuses grouped ethnic groups according to their mother tongue, the latter did not record separate constituent nationalities and reported all "Serbo-Croato-Slovene" speakers as "Yugoslavs".

Languages
The following data, grouped by first language, is from the 1921 population census:
 * Serbo-Croatian: 8,911,509 (74.4%)
 * Serbs, Macedonian Slavs and Montenegrins: 44.6%
 * Croats: 23.5%
 * Muslims of Yugoslavia: 6.3%
 * Slovene: 1,019,997 (8.5%)
 * German: 505,790 (4.2%)
 * Hungarian: 467,658 (3.9%)
 * Albanian: 439,657 (3.7%)
 * Romanian: 231,068 (1.9%)
 * Turkish: 150,322 (1.3%)
 * Czech and Slovak: 115,532 (1.0%)
 * Ruthenian: 25,615 (0.2%)
 * Russian: 20,568 (0.2%)
 * Polish: 14,764 (0.1%)
 * Italian: 12,553 (0.1%)
 * Others: 69,878 (0.6%)

Based on language, the Yugoslavs (collectively Serbs, Croats, Slovenes and other South-Slavic groups in the kingdom) constituted 82.9% of the country's population.

Religious groups

 * Christian: 10,571,569 (88.2%)
 * Eastern Orthodox: 5,593,057 (46.7%)
 * Roman Catholic: 4,708,657 (39.3%)
 * Protestant: 229,517 (1.9%)
 * Greek Catholic: 40,338 (0.3%)
 * Sunni Muslim: 1,345,271 (11.2%)
 * Jewish: 64,746 (0.5%)
 * others: 1,944 (nil%)
 * atheists: 1,381 (nil%)

Class and occupation

 * Agriculture, forestry and fishing – 78.9%
 * Industry and handicrafts – 9.9%
 * Banking, trade and traffic – 4.4%
 * Public service, free profession and military – 3.8%
 * Other professions – 3.1%