<p>When the inaugurating assembly of the World Council of Churches (WCC) met in 1948 questions about women's participation in the life and work of the churches, including the ordained ministry, were already on the agenda, placed there by women even though few women participated in any official capacity in the assembly. Since 1948 women's participation has become an increasingly important issue within the life and work of the WCC itself. This thesis, which is based on extensive primary research, documents and discusses women's participation in the WCC from that first assembly in 1948 to the seventh in 1991. By women's participation I understand both the inclusion of women among the representatives of the member churches who participate with some authority in the various policy and decision making bodies within the Council and the contribution of women's experiences, insights and perspectives to its policies and programmes. I argue that although women's participation in the WCC has increased significantly in the period 1948-1991 this increase has occurred only as a result of considerable struggle by women themselves, and that the ongoing pressure from women for their full and equal participation with men gives rise to serious tensions and problems within the WCC today. The basic approach is chronological, with documentation and discussion organised around the seven WCC assemblies held in the period 1948-1991. The slow processes of bureaucratic change through which women's participation has increased are documented in some detail, with particular attention given to their participation in assemblies and on the central committee, these being the two most powerful bodies in the governance of the WCC. Significant changes in the policies and programmes of the WCC resulting from women's participation are discussed, with particular attention paid to the "women's department" which, although its title and mandate have changed more than once, has consistently been the locus of advocacy for women's participation, and the commission on Faith and Order which has addressed theological questions raised by and about women's participation. The conclusion drawn from this study is that women's participation offers a number of significant challenges to the WCC and its member churches in their quest for unity.</p>