This chapter analyses four women intellectuals and activists in the Women’s International League for Peace and Freedom (WILPF). In the 1930s, Emily Greene Balch, Helena Swanwick, Vera Brittain and Mary Agnes Hamilton were public intellectuals, with a stake in the concrete policy debates of their time, which revolved around the questions of collective security and appeasement. Balch and Swanwick opposed collective security and embraced a pacifist position, while Hamilton and Brittain supported it. They all strategically invoked their gender, based on the intellectual traditions of suffragism and feminist pacifism that countered masculinist IR discourses. Though there was certainly no unanimity among them, they ‘turned an earlier misogynistic tradition on its head,’ by making a claim on representing ‘women’s perspectives’ on international politics. Their contribution to the academic debate on collective security was vital in its time. Yet, in the end, it was written out of IR’s intellectual history.