The aim of this essay is to discuss the possibility of applying knowledge from the field of sociology and other disciplines into the theory of public diplomacy. Due to changes in the international environment, public diplomacy (a complementary tool of foreign policy) is used for various foreign policy goals including spreading state influence. We identify the need for alternative approaches to public diplomacy especially within the domain of value and norm diffusion. Current prevailing concepts, such as state branding (derived from marketing discipline), do not prove to be effective in the political aspect of this field. This calls for the implementation of new approaches in international relations and diplomacy, particularly from sociology, psychology and communication studies. This article should stress the importance of transferring the knowledge from the above mentioned fields into the theory of public diplomacy—which has been neglected (or only now starting to gain importance) in the theory of international relations. It tries to draw attention especially of sociologists who have much potential to contribute to its development and analysis.