The concept of empire has known diff erent variants of theoretical understanding over a long period of its existence. By the 19th century, the focus of scholarly enquiry had shifted from the concept of empire to that of imperialism. In the 1860s-1870s, the idea of liberal imperialism, which was the harmonisation of liberal ideology and values with imperial attitudes and principles, began to take shape among the British intellectual elite. Although today there is no consensus concerning the very notion of empire, it seems possible to identify a number of features (including legitimacy, universalism and the desire to change the status quo as a cornerstone of foreign policy) that are characteristic of this phenomenon. The authors proceed from the hypothesis that the historical experience of the British Empire and the United States is an experience of practical implementation of the idea of liberal empire. The authors focus on the analysis of the peculiarities of foreign policy of the British Empire and the USA in the 19th and early 20th centuries. The authors conclude that the British Empire is a paragon of a liberal empire. The expression of that was Pax Britannica, a world order based on the legitimate power of the British Empire, which exported values under the guise of messianic ideas and played the role of arbitrator in maintaining "balance of power". The authors conclude that it seems possible to consider the US as a post-colonial liberal empire (hegemony). Although there is a lot of talk about the crisis of liberalism and the erosion of American infl uence, the current world order still functions on the basis of the US-led international institutions and shared commitment of the developed countries to liberal values.