This paper focuses on the dynamic processes working through cultural tourism development in the Calabrian region of southern Italy. Exploring how such processes are interconnected is needed to sustain tourism development. Calabria is located in the extreme south of the Italian peninsula, the “toe of Italy.” It is said to be the last undiscovered place in Italy, sometimes called “a forgotten Italy.” Since the 19th century, Calabrian locals have been emigrating to northern Italy or even to the USA or South America to seek good jobs and to earn money. This has prevented the Calabrian region from developing into a modern tourism destination. On the other hand, Calabria has a rich culture and splendid natural resources for attracting tourists and conserves authentic local traditions in spite of globalization. Long interviews have been conducted with 30 Calabrian locals in some places facing the Ionian Sea on the east side of Calabria about positive and negative factors for tourism development. Based on these interviews, a causal network was constructed, and its network nodes were inputted into a mathematical model to explore the dynamic processes during the modern era in Calabria. Results indicate that the interrelationship of positive and negative factors for tourism development can be partly explained using the proposed mathematical model. Considering the model, the key factors in sustainable cultural tourism development depend on the effort to weaken negative factors that deteriorate the target society. Moreover, basic infrastructure development has been proven to be particularly needed for tourism in Calabria.