This paper addresses the emergence of the Organization of Communist Unity (Sazman-i vahdat-i kumunisti) which formed out of the Popular Front of Iran (Jibhih-yi milli-yi Iran) and its Organizations abroad, and the process by which it came to publicly advocate the principles of armed struggle and internationalist proletarian solidarity. Much like the Cuban Fidel Castro or the Palestinian George Habash, these men and women began as anti-colonial nationalists, who steadily concluded that American imperialism, the world capitalist system and the oppression and exploitation they both perpetuated were inextricably intertwined. The only antidote was held to be revolutionary socialism and the overthrow of the Pahlavi ancien régime. These individuals were crucially shaped by a foundational trauma, namely the MI6-CIA orchestrated overthrow of the nationalist government of Muhammad Musaddiq, for which they held foreign imperialists and home-grown reactionaries responsible. These events gave rise to the search for a radical explanation and alternative to the authoritarian impasse, which had made civil contestation of the political order well-nigh impossible. The Organizations of the Popular Front Abroad sought to represent the Popular Front inside Iran, the original umbrella of disparate groupings and political personalities formed in 1949, which pioneered the nationalisation of the Anglo-Iranian Oil Company in 1951 and the Musaddiq government’s defence of the principle of nationalisation to the great chagrin of Britain’s Labour and Conservative governments. Several of these young nationalist students who had been sent abroad to continue their studies during the 1960s found themselves radicalised while residing in the metropole and against the backdrop of the waves of decolonization and resistance to imperial interventionism. Understanding how Communist Unity emerged out of the Organizations of the National Front Abroad, and its conversion to the cause of armed struggle illuminates several key ideological and political debates of the period. While also demonstrating how Iranian activists’ participation in the Tricontinental Moment converged and coincided with that of other regional and international actors, resulting in novel modalities of political praxis and theorising within the Iranian context. The paper draws upon memoir literature, but more crucially, newspapers, pamphlets and tracts published and disseminated by Vahdat, as well as the Organizations of the National Front of Iran.