Summary Translation is not an isolated field of activity. It is closely related to the certain historical, political, ideological, socio-cultural, and sociolinguistic context of a country, i.e., translation depends on polysystems of a particular period of time. The article examines two different translations of Moliere’s play “The Tartuffe” into Lithuanian. “The Tartuffe” was first translated by Čiurlionienė-Kymantaitė in 1928 and later in 1967 by Churginas. This research is based on the polysystem theory of Even-Zohar and Toury’s theory of norms in translation. For the analysis of the translations of the theatre play, proper nouns were chosen as the object of the research. The analysis was done using comparative, linguistic descriptive and quantitative methods. These methods assisted in comparing decisions of translation used to translate proper nouns of “The Tartuffe”. Moreover, the analysis reveals the tradition of translation of proper nouns and the changes during the Interwar and Soviet Lithuania periods. In order to achieve the aim of the research, the objectives are as follows: to discuss the activity of translation as a part of the polysystems, to select and classify proper nouns of the research material according to translation decisions chosen by each translator, to review its validity and to discuss translation changes of Lithuanian translation tradition from the beginning to the end of XX century. After a comparative study of the translation of personal nouns in the research material, the author identifies and discusses five translation decisions: phonetic adaptation, omission, grammaticalization of the authentic form, replacement into another proper noun and actualization. Both translators mainly used phonetic adaptation, i.e., linguistic application of proper nouns. Looking towards both translations from the perspective of the social norms theory of Toury and the theoretical concept of polysystemical and binary oppositions of Even-Zohar, it can be assumed that translating Moliere’s play “The Tartuffe”, which belongs to the world literature canon, both translators (Čiurlionienė-Kymantaitė and Churginas) accepted the translation challenges of classical literature, understood the value of the work and the importance of maintaining the uniqueness of this theater play which belongs to Classicism. A comparative analysis of translation of the proper nouns allows identifying the dynamic formation of the tradition of proper nouns translation and its changes in Lithuania starting from quite diverse decisions of translation during the Interwar period, which was characterized by a free translation market, unrestricted selection of translations and their adaptation to the sociocultural and linguistic expectations of the readers, to the development of centralized and institutionalized norms in translation during the period of Soviet Lithuania, which was marked by unanimously applied rules of translation of the proper nouns and norms of the standard Lithuanian language. The results of the comparative research of the translation of the proper nouns allow us to confirm that the first translation, published in 1928, introduced Molière’s play to the Lithuanian culture of translation but became obsolete. Thus, almost forty years later, in 1967 there was a need for a new version of translation of “The Tartuffe” that would be adapted to a contemporary period in which cultural systematic knowledge and the usage of cultural elements and language differed from the first translation version.