The term "Polish-Lithuanian union" means a development from personal union between the Kingdom of Poland and the Grand Duchy of Lithuania to the creation of the Polish-Lithuanian Commonwealth — the "Republic of the Two Nations" — in 1569 and eventually to the creation of a short-lived state in 1791.
The most important acts in the process of union were:
- 1385 - Union of Krewo - a personal union;
- 1401 - Union of Vilnius and Radom;
- 1413 - Union of Horodło;
- 1432 (1432-34) - Union of Grodno;
- 1499 - Union of Kraków and Vilnius;
- 1501 - Union of Mielnik;
- July 1, 1569 - Union of Lublin - creation of the Republic of the Two Nations;
- May 3, 1791 - Polish Constitution of May 3, 1791: the Kingdom of Poland and the Grand Duchy of Lithuania were abolished, and a common state was created in their place.