From its onset, the labour movement developed an internationalist perspective, challenging the foreign policies of their own waring bourgeoisie. In Marx’s inaugural address at the First International in 1864, he argued that the fight for a foreign policy based on morals and justice ”forms part of the general struggle for the emancipation of the working classes”. The Second International, with mass social democratic parties across Europe, famously collapsed after most member parties supported the war machines in their own countries and the mass slaughter of WWI. After the successful workers’ revolution in Russia in 1917, the Third International was founded to oppose the war, support national liberation struggles of colonised peoples and to organise the world revolution. It was officially disbanded in 1943, after many of its leading members were purged and executed under Stalinist terror. In reaction to Stalinism, Trotsky founded the 4th International in 1938 – it was never to gain mass support and later split into various factions. The seminar dives into the history of the different Internationals, using many primary documents from the conferences. What lessons can be learnt from the history of the international relations of the labour movement for the 21st Century? In the age of Globalisation, what kind of internationalist and transnational cooperation is developing today?