The Legacy of the Filibuster War: National Identity, Collective Memory, and Cultural Anti-Imperialism is a dissertation project analyzing how the Filibuster War becomes a staple for Costa Rican national identity. This work presents several challenges to traditional theories of modernization in the creation of nationalism. By focusing on the development of cultural features defined by the transformation of collective memory, this project argues that national identity is a dynamic process defined according to local, national, and international contexts. Modernization theories connect the development of nationalism to the period of consolidation of the nation-state, usually during the late nineteenth century and early twentieth century. The Costa Rican case demonstrates that, while modernization coincides with the creation of symbols of official nationalism, the Filibuster War became a symbol of national identity beginning in the 1850s, and it has been changing throughout the twentieth century. Threats to sovereignty and imperialist advances served to promote the memory of the Filibuster War, while local social transformations, as the abolition of the army and internal political conflict forced drastic changes on the interpretation of the war and the establishment of a national narrative that adjusts to social transformation.