The internationalization of women's organizations and of teachers' associations during the "long 1920s" provided a context for English women educators to test and discuss their ideas concerning the girls' secondary school within European transnational networks. This exploration of social change adopts a Bourdieusian and transnational approach to analysis of strategies for change within two international organizations: the International Federation of University Women and the Bureau international des Federations nationales du personnel de l'Enseignement secondaire public. It argues that the contribution of English women educationists to European debate regarding girls' secondary education was related to their location in communities of interpretation within wider political, professional and educational fields in which gender carried different amounts of symbolic capital in different contexts. These fields, in turn, were implicated in wider change around the position of women in society, with education for girls operating as both a conservative force and a force for change. At the same time, the "idea" of the girls' secondary school was validated through comparative investigation of girls' secondary education in Europe with a methodology in which particular notions of social change were embedded. (Contains 73 footnotes.)