The dissertation presents an analysis of the development of maritime affairs in Dubrovnik during monarchist Yugoslavia, as well as their connection to and influence on the economy of Dubrovnik. The development of maritime affairs is considered through the operation of Dubrovnik’s shipping companies, the Port of Gruž, and maritime educational institutions in Dubrovnik (the Nautical School of Dubrovnik “Nautika” and the Naval Academy of Dubrovnik). The research is based on archival material found in the National Archives in Dubrovnik, the Croatian State Archives in Zagreb, and the Archives of Yugoslavia in Belgrade, along with material found in contemporary press and relevant literature. Even before World War I, as well as during the Interwar period, maritime affairs had a significant role in the economy of Dubrovnik. However, the conditions for the development of maritime affairs within the context of monarchist Yugoslavia were unfavourable given the lack of understanding and the disinterest of the highest government and political circles regarding maritime affairs. Furthermore, global circumstances also had a negative impact on maritime affairs; the Interwar period was marked by the Great Depression (1929–1933), while global maritime transport saw its own crisis starting immediately after World War I and lasting until the period of conjuncture preceding World War II. Dubrovnik’s shipping companies established themselves as prominent actors within the local framework, and their contribution to the overall national maritime development was significant. Companies noted for their success in business (Dubrovačka parobrodska plovidba and Jugoslavenski Lloyd) enjoyed the support of the ruling establishment, and the extent of their development can partly be attributed to state subsidies. In spite of all circumstances, maritime affairs were a foundational element of the economy of Dubrovnik during the Interwar period due to their significant impact on the employment rate of the working-age population and the investment of the shipping industry capital in other segments of the economy. Maritime affairs also contributed to the development of tourism in Dubrovnik, primarily with cruise tourism establishing itself as a specific form during the Interwar period and remaining an important part of tourism in 21st century Dubrovnik.