It is a fact seldom noted, either through ignorance or as too obvious to deserve mention, that the modern missionary movement was driven in large part by the enthusiasm and commitment of the young. At no time was this more the case than in the period c.1880–1918 when the growth of western missions overseas reached its peak, coinciding with the classical age of European imperial and colonial expansion. Of approximately 10,000 British missionaries active in 1900 by far the greatest proportion was of young unmarried women or students fresh from college and university. However, it is only in the last few years that scholars have begun to explore the implications of this observation, and, as Ruth Franzen's book recognises, there remains much scope for investigation. At the heart of her essentially biographical study is the career of the Anglican mission organiser Ruth Rouse (1872–1955). Thwarted by illness in her ambition to become a missionary to India, Rouse won an international reputation for herself in her role as international travelling secretary for the World Student Christian Federation from 1897 to 1924. The WSCF was one of the most far-reaching evangelistic organisations spawned by the student Christian movement. It was rooted in the revivalism of the late nineteenth century, drew on the traditions of the Young Men's/Women's Christian Association, and was important in the long run as a nursery of both ecumenical sentiment and leaders of the World Council of Churches established in 1948. Illustrative of historiographical neglect is the almost total absence, even among historians of religion, of any interest in either Rouse or the WSCF. Eugene Stock's history of the Church Missionary Society merely dismissed their 1911 Constantinople conference involving orthodox Christians in the Muslim world as something that ‘needless to say, came to nothing’. The nineteenth and twentieth century volumes of the recently published Cambridge history of Christianity (2006) includes only one, barely meagre reference and that to the WCC. Frantzen's achievement is thus a notable one. She offers the first significant study of one of those female mission administrators then beginning to emerge as leaders of the principal missionary societies. Georgina Gollock, Literature Secretary at the Church Missionary Society and Assistant Editor of the International Review of Missions might well provide an instructive comparison. This is also a work that parallels C. Howard Hopkins's biography of the American student leader John R. Mott, not least in its providing a quarry for women's history, historians of evangelicalism and the dynamics of global history. Franzen shows the extent of Rouse's central achievement in drawing women steadily into the WSCF and main-stream mission organisation on an equal footing with men in the years 1905–20. This developed from her organisation of parallel womens' conferences alongside their male counterparts, her identification with the missionary slogan of the age – ‘the evangelization of the world in this generation’ – her close co-operation with Mott, and her indefatigable networking in pursuit of Christianity's global unity. Indeed, Mott's reputation seems likely to require reassessment in the light of Franzen's argument that Rouse was an important and persistent source of inspiration and contacts for him and his colleagues in their campaigning. No longer were the contributions of females to be confined to an intellectual ghetto labelled ‘women's issues’. Light is also shed on associated themes, such as the impact of the First World War on international missionary planning. A final chapter summarises Rouse's later career as ‘promoter of missions at home’ and historian of the ecumenical movement.