French religious life in the mid-seventeenth century was conspicuous for its revolutionary reversal of Tridentine prescriptions enforcing strict claustration upon women religious. In the process modes of female piety changed from contemplative to active within the development of a number of active female religious congregations dedicated to working beyond the cloister to provide key social and welfare services to communities. This study explains the genesis of this active female apostolate in the seventeenth century. It is a comparative examination of the first three of these orders, which spearheaded this development; the Order of the Visitation, the Daughters of the Cross and the Daughters of Charity. The work initially examines the Visitandines, the first female religious order seriously to challenge Tridentine prescriptions on claustration. Although in the long run they failed in their attempt, this order served as an influential example and created powerful networks of people of influence and means who would go on to support future orders. The second order, the Daughters of the Cross, was the first to benefit from their 'mistakes' and networks. Although they developed on a small scale, the highly significant Paris-based community, unrestricted by claustration, dedicated itself to professional teaching services. The third and the biggest success story, the Daughters of Charity, drew on the experience of these two groups, and exploited networks of influence and finance. They circulated freely in the community and worked to provide community servies on a national and subsequently international scale. My thesis is concerned with the interaction between founders, supporters, particular bishops and the women themselves and the acts of collusion which finally achieved this radical change. It aims to identify an initially tentative process which gained in the course of 50 years considerable momentum and radically transformed religious life for both women and for social Catholicism.