During the Polish–Lithuanian union, there was an influx of Poles into the Grand Duchy of Lithuania and the gradual Polonization of its elite and upper classes.

[5] Polonization also affected Lithuanian and Belarusian peasants and led to the formation of a long strip of land with a predominantly Polish population in the late 19th century, stretching to Daugavpils and including Vilnius.

[19] The local variety of Polish called Polszczyzna Litewska became the native tongue of the Lithuanian nobility in the 18th century.

[25] Most of Poles who live southwards of Vilnius speak a form of Belarusian vernacular called there "simple speech",[26] that contains many substratical relics from Lithuanian and Polish.

[33] Poles started to migrate to the Grand Duchy in more noticeable numbers after Christianization of the country and establishment of the union between Poland and Lithuania in 1385.

[34] In the 15th-16th centuries, there were not many Poles in Lithuania, but they enjoyed a privileged social status – they were found in highly regarded places and their culture was considered prestigious.

While Poles and foreigners were generally prohibited from holding public offices in the Grand Duchy, Polish people gradually gained this right through the acquisition of Lithuanian land.

[50] Vilnius became the most important center of the Polish intelligentsia in the Grand Duchy,[51] with Poles predominating in the city in the mid-17th century.

[55] During the Commonwealth, a Polish-dominated territory started to be slowly formed in the Grand Duchy of Lithuania,[34] such as Liauda, northeast of Kaunas (since the early 15th century).

[34] Until the 1830s, Polish was the administrative language in the so called Western Krai, which included the territories of the Grand Duchy of Lithuania that were annexed by the Russian Empire.

[61] In the 19th century, Polish culture spread among the lower classes of Lithuania,[62] mainly in Dzūkija and to a lesser degree in Aukštaitija.

[64] The position of Vilnius as an important Polish cultural center influenced the development of national identities among Roman Catholic peasants in the region.

The irredentist demand for its recovery became one of the most important elements of socio-political life in interwar Lithuania and resulted in the emergence of hostility and resentment against the Poles.

By 1928, 2,997 large estates with a total area of 555,207 ha were parceled out, and 52,935 new farms were created in their place and given to Lithuanian peasants.

[citation needed] The most tragic episode in the history of Poles in interwar Lithuania was an anti-Polish demonstration organized by the Lithuanian Riflemen's Union on May 23, 1930 in Kaunas, which turned into a riot.

[84] In most cases, the Soviet authorities blocked the departure of Poles who were interwar Lithuanian citizens and only 8.3% (less than 8,000) of those who registered for repatriation in Kaunas Region in 1945–1946 managed to leave for Poland.

[87] The Polish minority increased in size, but more slowly than other ethnic groups in Lithuania; the last Soviet census of 1989 showed 258,000 Poles (7.0% of the Lithuanian SSR's population).

[89] Due to their view of ethnicity as primordial, they argued that the Lithuanian state should work to restore their "true" identity.

[92] Simultaneously, after the August Coup's failure, the Polish autonomous region was immediately declared illegal by the Lithuanian government, which instituted direct rule in those areas.

On 29 January 1991, Lithuanian government granted minorities right of schooling in their native language and use of it in official institutions.

In 1996, the special provisions that made an entry of ethno-political parties parliament easier were removed, and from then on they had to meet the usual electoral threshold.

The restoration of property lost during the communist period was also a burning issue, which was implemented very slowly in the lands inhabited by Poles.

Until 2010, Lithuanian-Polish bilingual street signs were considered legal in Lithuania if placed in the areas with significant Polish populations.

[131][135] The official spelling of the all non-Lithuanian (hence Polish) name in a person's passport is governed by the 31 January 1991 Resolution of the Supreme Council of Lithuania No.

In the passport of a citizen of the Republic of Lithuania, the first name and surname of persons of non-Lithuanian origin shall be spelt in Lithuanian.

At the same time, it was stressed out citizen's rights to spell their name whatever they like in areas "not linked with the sphere of use of the state language pointed out in the law".

[138] In 2022, the Seimas passed a law allowing members of ethnic minorities to use the full Latin alphabet, including q, w and x, letters which are not considered part of the Lithuanian alphabet, but not characters with diacritics (such as ł and ä), in their legal name if they declare their status as an ethnic minority and prove that their ancestors used that name.

In response, several ethnically Polish Lithuanian politicians changed their legal names to be closer to the Polish spelling, most notably Justice Minister Ewelina Dobrowolska (formerly spelled "Evelina Dobrovolska"), but requests for name changes from the general population were low.

[139][140] From May 2022 when law came into action until the end of July 2023 only 337 people changed their names to include non-Lithuanian language symbols and only less than 5 of those declared to be of Polish descent.

[141] By the end of August 2023 the number of people of Polish descent that changed their names to include non-Lithuanian symbols increased to 203 which was approximately 0.11% of all Poles in Lithuania.