The purpose of this article is to reconstruct the liberal theory of foreign policy by showing its ontological and epistemological premises followed by analytical application. The theory, invoking liberal ideas and values, was first developed in the 1970s, and its main principles were formulated after the end of the Cold War, mainly in opposition to structural realism, according to which the international system is the key determinant of the international activity of states. While not negating the significance of external factors, representatives of the liberal school point out that internal factors play an equally important role. For example, it matters whether the internal political system of a given state is democratic or authoritarian. Consequently, the two systemic determinants are approached in an analogous manner. The second and third parts of the article are dedicated to the analysis of the foreign policy of Western countries and the United States in terms of the liberal model of foreign policy, which can be perceived as the explanans – an analytical tool.