The article presents the issue of extramarital births in the parish of Nowy Korczyn in the years 1751–1800. The analyses were conducted using an aggregate method. In the birth records of the Nowy Korczyn parish, in the second half of the eighteenth century, 179 baptisms of illegitimate children were recorded, constituting 4.4% of all births. Such a percentage of births out of wedlock is similar to the results obtained for other urban‑rural parishes. Illegitimate births occurred significantly more often in the urban than in the rural part of the parish. In the Nowy Korczyn parish, there was a clear concentration of conceptions of illegitimate children in the spring and summer months. Twin births constituted a significantly larger percentage among illegitimate births than among legitimate births. Birth records do not contain too much information about the parents of illegitimate children, so the description of the social environment of people having such offspring is quite difficult. Most often, the data recorded in the records are limited to the name and surname of the mother. Fathers remain essentially anonymous in the records. It is known that a significant group of mothers of illegitimate children were migrants, but their territorial affiliation in the records remains a mystery. The baptismal names given to illegitimate children did not differ from the names given to legitimate offspring, although it is known that the parish clergy often stigmatized illegitimate children by giving tchem unusual and rarely occurring names. The selection of appropriate godparents for a child played an important role at that time. However, given that the social environment of the parents of illegitimate children has not been precisely identified, it is not possible to analyze their selection. Giving birth to an illegitimate child did not condemn a woman to lead a solitary life, as some of them later entered into marital relationships. The records also noted that some women had more than one child out of wedlock.