The Polish-Lithuanian identity describes individuals and groups with histories in the Polish–Lithuanian Commonwealth or with close connections to its culture. This federation, formally established by the 1569 Union of Lublin between the Kingdom of Poland and Grand Duchy of Lithuania, created a multi-ethnic and multi-confessional state founded on the binding powers of national identity and shared culture rather than ethnicity or religious affiliation. The term Polish-Lithuanian has been used to describe various groups residing in the Commonwealth, including those that did not share the Polish or Lithuanian ethnicity nor their predominant Roman Catholic faith.

The Krajowcy were a group of mainly Polish-speaking intellectuals from the Vilnius Region who, at the beginning of the 20th century, opposed the division of the former Polish–Lithuanian Commonwealth into nation states along ethnic and linguistic lines. The movement was a reaction against growing nationalism in Poland, Lithuania and Belarus. The Krajowcy attempted to maintain their dual self-identification as Polish–Lithuanian rather than just Polish or Lithuanian. The Krajowcy were scattered and few in number and as a result failed to organize a widescale social movement.