The Western Ukrainian clergy of the Ukrainian Greek Catholic Church were a hereditary tight-knit social caste that dominated Western Ukrainian society from the late eighteenth until the mid-twentieth centuries, following the reforms instituted by Joseph II, Emperor of Austria. Because, like their Orthodox brethren, Ukrainian Catholic priests could marry, they were able to establish "priestly dynasties", often associated with specific regions, for many generations. Numbering approximately 2,000-2,500 by the 19th century, priestly families tended to marry within their group, constituting a tight-knit hereditary caste. In the absence of a significant culturally and politically active native nobility (although there was considerable overlap, with more than half of the clerical families also being of petty noble origin ), and enjoying a virtual monopoly on education and wealth within western Ukrainian society, the clergy came to form that group's native aristocracy. The clergy adopted Austria's role for them as bringers of culture and education to the Ukrainian countryside. Most Ukrainian social and political movements in Austrian-controlled territory emerged or were highly influenced by the clergy themselves or by their children. This influence was so great that western Ukrainians were accused by their Polish rivals of wanting to create a theocracy in western Ukraine. The central role played by the Ukrainian clergy or their children in western Ukrainian society would weaken somewhat at the end of the nineteenth century but would continue until the Soviet Union forcibly dissolved the Ukrainian Greek Catholic Church in Ukrainian territories in the mid-twentieth century (the so-called Council of Lviv, 1946).
In 988 East Slavic state of Kyivan Rus was converted to the Eastern form of Christianity at the behest of Volodymyr I of Kyiv. Following the East-West Schism between the Roman and Byzantine Churches, the form of Christianity that Kyivan Rus followed became known (in English) as the Eastern Orthodox Church. The westernmost part of Kyivan Rus formed the independent Kingdom of Galicia–Volhynia, which Poland conquered in 1349. Over the following centuries, most of the native landowning nobility adopted the dominant Polish nationality and Roman Catholic religion. Only the poorer nobles, descended from a mixture of poor boyar families, druzhina (free warriors serving the princes), and free peasants, retained their East Slavic identity. Many priestly families had origins among those poor nobles. and in some particular regions, such as the area between Lviv and the Carpathian mountains, almost all of the priestly families were of poor noble origins. Such people identified themselves primarily as priests rather than nobles. Thus, the local native society was composed principally of priests and peasants. In an attempt to limit Polish pressure, the Union of Brest (1595/1596) saw the creation of the Uniate Church (later the Ukrainian Greek Catholic Church) in the former parts of Kyivan Rus under Polish rule. Like other Eastern Catholic Churches, the Uniate Church maintained the liturgical, theological and devotional traditions, including married priesthood, of the Orthodox Church - despite its new allegiance to Rome.