The article analyses the causes of the lack of lasting and stable cooperation between Poland and Russia. The fundamental research question posed by the author is: Are countries who rely on different theoretical paradigms in their international relations able to engage in lasting cooperation with each other? In the study, the author uses the instrument of analytical eclecticism, understood also as the response to the request for pragmatism in the approach to studies of international relations in the broad sense, as well as two theoretical approaches, a different one for each country: the liberal paradigm for Poland and the realist paradigm for Russia. The analysis of these countries’ foreign policies has been conducted is based on three criteria: their perception of the nature of the relations between states from the liberal and realist angles, their perception of international regimes and institutions as platforms for cooperation and the means and sources used for identifying their interests. The article is divided into four parts. In the first part, the author constructs the analytical model to be used in the further parts. In the second part, the author reconstructs the Polish perception from the liberal angle using the aforementioned three criteria. The third part contains a similar reconstruction of the Russian perception based on the realist approach. The last part of the article is dedicated to the Polish and Russian perception of two selected problems: the significance of Ukraine for each of the two countries and the optimal shape of the European security architecture. The study presented in the article leads to a positive answer to the research question posed in the introduction. It seems, therefore, that similarity – or, in this case, dissimilarity – between the states’ perceptions of the international reality constitutes a crucial factor facilitating or hampering lasting and stable cooperation.