During World War I industrial welfare work was firmly established as an occupation, especially in munitions factories under the Ministry of Munitions. This article explores the significance of the fact that the majority of the welfare supervisors employed during the war were women. Welfare supervisors are one example of the ways in which middle-class women grasped career opportunities offered by the war. Much of their work epitomized contemporary concepts of ‘womanly' duties and was designed to protect women workers as mothers of the race. Women welfare supervisors were caught between the proto-welfare state's espousal of the ideology of maternalism, and their aspirations to professionalism. To claim the status of professionals meant, not only proving their abilities, but also conforming to masculine norms of efficiency, rationality, expertise, organisation and status. By the end of the war, women welfare supervisors who sought to stay in the field had built a strong central organisation which proclaimed industrial welfare work as a professional part of management. Women's entry into the managerial level through welfare work, consolidated after the war, challenged the patriarchal hierarchy and traditions of business and industry. Thus women welfare supervisors juggled the feminine and masculine definitions of their work, but increasingly stressed its masculine managerial dimensions to claim management status.