The Balkan Federation was a project about the creation of a Balkan federation or confederation, based mainly on left political ideas.
The concept of a Balkan federation emerged at the late 19th century from among left political forces in the region. The central aim was to establish a new political unity: a common federal republic unifying the Balkan Peninsula on the basis of internationalism, socialism, social solidarity, and economic equality. The underlying vision was that despite differences among the Balkan peoples the historical need for emancipation was a common basis for unification.
This political concept went through three phases in its development. In the first phase the idea was articulated as a response to the collapse of the Ottoman Empire at the beginning of the 20th century. In the second phase, mostly through the interwar period (1919–36), the idea of the Balkan federation was taken up by the Balkan communist parties. The third phase is characterized by clash between Balkan communist leaders and Joseph Stalin as an opponent of the idea during the post-World War II period.
At first, in Belgrade in 1865 a number of radical Balkan intellectuals founded the Democratic Oriental Federation, proposing a federation from Alps to Cyprus based on political freedom and social equality. They confirmed their adherence to the ideals of French Revolution in the line of Saint-Simon's federalism and in relation to the socialist ideas of Karl Marx or Mikhail Bakunin. Later, in France, a League for the Balkan Confederation, was constituted in 1894, in which participated Greek, Bulgarian, Serbian and Romanian socialists, supporting Macedonian autonomy inside the general federation of Southeast Europe, apprehending the complexity of the Macedonian Question. The next attempt came immediately after the Young Turk Revolution in 1908. The following year, in Salonika the Socialist Workers Association merged with two Bulgarian socialist groups and the Socialist Worker's Federation of Ottoman Workers was founded. Although it underestimated, till 1913, the political significance of the national question, as this significance manifested itself in the right of national self-determination, and its leadership kept a moderate position in regard with the nationalistic tendencies in Balkan social-democratic parties.