The reviewed collective study “Cultural Complexity of Modern Nations” is devoted to the actual issues of nation and state building. These problems are considered within two frameworks of the world complexity: internal cultural identity diversity of the inhabitants of modern nation-states and plurality of country cultural patterns of these states at their different historical stages. Pluralism and multivariance of the modern world development have prompted the authors of this work to develop new conceptual approaches to the categorization of this world and to consider social processes within new analytical reference systems. Researchers are expanding the notion of diversity, making it even more versatile and accentuating its style difference component. Multiculturalism as a model of management of cultural differences in the “old” nations is presented in different guises – not only as a collapsed European integration project. This approach shows viability on the Australian continent. And according to Berlin example, many successes are on account of the successor of such policies, interculturalism, at the local level. The authors realize a fruitful “revision” of the used category of the nation, to which a plural meaning is attached. They demonstrate a transient nature, socio-political and regional specificity of this phenomenon, multiplicity of forms of nation and state formations. Hybrid, centaur-like type of new collectivities that emerged in the postcolonial period, is generated by their borrowing political institutions and norms of Western societies and the imposition of foreign models into inappropriate social and cultural environment. Pondering over the destiny of nations in the world, which is becoming postnational, the authors raise the possibility of the formation of post-national states. Probably one of the characteristics such social coalitions will be the abandonment of national sovereignty as the main attribute of the state in favor of trans-state institutions of governance. Their modern examples are transnational unions, cross-border religious communities as a kind of nation-community, created on the basis of faith.