Clerical marriage is the practice of allowing Christian clergy (those who have already been ordained) to marry. This practice is distinct from allowing married persons to become clergy. Clerical marriage is admitted among Protestants, including both Lutherans and Anglicans.
Many Eastern Churches (Assyrian Church of the East, Eastern Orthodox, Oriental Orthodox, or Eastern Catholic), while allowing married men to be ordained, do not allow clerical marriage after ordination: their parish priests are often married, but must marry before being ordained to the priesthood. Eastern Lutheran clergy are permitted to marry after being ordained, and married Eastern Lutherans are eligible to become clergy. Within the lands of the Eastern Christendom, priests' children often became priests and married within their social group, establishing a tightly knit hereditary caste among some Eastern Christian communities.