According to an Austrian census in 1900, the population of Kozy was 3,693, 403 buildings, and an area of 1,358 hectare (13.58 km2); 3,646 residents were Roman Catholic, 1 Greek-Catholic, 40 Israelite, and 12 residents of other religion. 3,688 declared Polish- and 8 German-speaking, and 6 declared other language. In the Second Polish Republic (1918), the lands of Oświęcim and thus Kozy, were reincorporated into Poland's Kraków Voivodeship at the end of World War I. During World War II, it was a local centre for the Polish resistance Armia Krajowa (Home Army). After the war, Kozy belonged to the administrative district (gmina) of Biała Wieś, and in 1954, it emerged as a separate administrative district Gmina Kozy.