The purpose of this article is to reveal the causes of national and cultural identity crisis of Serbs in Bosnia and Herzegovina during the period of Austro-Hungarian occupation and annexation, which led to modifications of their self-identity. The paper meets this research aim through an extensive study of the relevant literature presenting the views of Serbian and Russian scholars. On the basis of comparative-historical and socio-cultural approaches, the authors collate the existing definitions of ethnic, national and cultural identity and define the crucial factors that make the cornerstone of cultural identity: mother tongue, ethnicity, territory, religion, habitat, food, mode of life, customs and traditions, folklore and literature, artwork and historical past. They go on to chronologically identify the developments and changes of society on the territory of the present-day Bosnian state. The article further analyzes the position of the peoples of Bosnia and Herzegovina within Austria-Hungary comparing their status in society and explains the choice of Bosnian Muslims and Croats as the pillar of the new government. The research produced a number of key findings. The key determinants that formed and helped to preserve Serbian cultural identity through ages are Orthodox Christianity based on St. Sava sacred tradition and the Kosovo myth, a half-historical, halflegendary event that formed the heroic and spiritual code of values and serves as a gospel in preserving Serbian cultural identity. Another feature that produced a significant impact on transforming cultural identity of Bosnian Serbs was conversion to Islam on part of some Bosnians who came to be known as Bošnjaks. Along with Islam and Orthodox Christianity, part of the Serbian population of Bosnia and Herzegovina belonged to the Roman Catholic Church, identified themselves as Croats who spoke Croatian and used Latin script. Thus the indigenous south Slavonic ethnic group of Serbs who had the same historical background and spoke the same language was divided by religion and, partially, the language — the pivotal determinants of identity. The paper demonstrates the joint efforts of the peoples inhabiting the present-day Bosnia and Herzegovina in their struggle against the occupants which were manifested in the activities of Young Bosnia, an organization that aimed at preserving national identity and creating a united Serbian state. The authors conclude that the problem of national and cultural identity crisis of Bosnia and Herzegovina Serbs finds its roots in the historical clash of three civilizations and cultures — south Slavonic, oriental and western. The article identifies the markers of national and cultural identity of Bosnia and Herzegovina Serbs, the disintegration of which led to a crisis.