The Polish post-communist party Social Democracy of the Republic of Poland (Socjal-demokracja Rzeczypospolitej Polskiej, SDRP) which survived almost unchanged in the dynamic Polish political scene of the 1990s was one of the leading political parties after 1989. This paper will attempt to explain the ideological journey, which has been taken by the former high-ranking Polish United Workers’ Party members after 1989. Their journey seems to start at the point of internationalism and socialism and ends in the victorious battle to join the European Union. Was this a simple modernized adjustment of the internationalist ideology or an opportunistic choice made in order to survive in the new political and social circumstances? Was choosing a pro-EU policy a choice or a necessity? This analysis will attempt to answer the above questions and describe this phenomenon of change or may be just an ideological continuity.