A union between two persons of opposite sex bringing certain mutual rights and responsibilities provided for in the provisions of law and customs.

In Poland only monogamous married couples are taken into account, which means that one person cannot be married to several persons at the same time. Current statistical reports cover only marriages joined under the law in force. Since December 15, 1998, under concordat-related law, church religious marriages with civil law effects resulting from the so far marriages performed in the Office of the Registrar of Vital Statistics, are also performed. In general censuses of population, marital status is established on the basis of voluntary declarations. In the 1988 census, only actual marital status was registered, not civil law, whereas in the 2002 census, information on both was collected. Civil pacts of solidarity are also distinguished.