The League of Nations was the first permanent international organisation with a general mandate. Its establishment is widely regarded as having had a significant, if elusive, impact upon international law, which became centred on international institutions. These three aspects of the League – its permanence, the generality of its mandate, and the ’institutional turn’ it brought to international law – lie at the heart of the assumed significance of the League for contemporary international lawyers. They are regarded as the League’s principal innovations and central components of its legacy, often without much interrogation and rarely subject to sustained analysis. This chapter offers analysis and interrogation to nuance claims about the League’s innovations. It presents the League as an institution whose grand designs often failed, but which innovated quietly and gradually. Above all, it shifts the focus away from the perceived ’breakthrough’ of 1919, and highlights the evolutionary nature of the League, which adapted throughout its life.