Since its foundation in 1919 the International Labour Organization (ILO) has regarded the worldwide eradication of forced labour as one of its basic aims. This article looks at the ILO's role both as a forum for public discourse on the historically shifting boundaries that separated free labour from coercion, and as an independent actor in the struggle against forced labour throughout the twentieth century. Examining the ILO's efforts in three distinct phases (the inter-war period, the Cold War years and the age of decolonization/postcolonial nation-building) will also shed light and contribute to the discussion on the influence of international organizations in the making of the modern world.