The feminization of Boards has the potential to be a vector of change, bringing "added value" to organisations through gender diversity, thus creating greater efficiency. Promoting women to positions of power only makes sense, however, if these women are allowed to bring, in terms of skills and behavior, a difference to the table. This involves confronting the masculine model, in order to BUILD a model of mixed leadership integrating the "feminine" quotient (A.Arcier). A qualitative study on women and their relation to power, undertaken in France and abroad (published in October 2012), allowed the formulation of some hypotheses in order to construct a proposition of a mixed power model that would integrate both masculine and feminine "polarities" within enterprises and organisations (ValerieRocoplan).This article is the outcome of various influences: the data of this study (by the same author with the support of the firm Boyden) which was further enriched by the analysis of other publications on the subject, as well as the experience acquired within the framework of the program Women Be European Board Ready (created by ESSEC). The article deliberately focuses on the issues surrounding gender and governance in order to address the smooth and effective running of Boards. The study essentially aims to highlight the fact that women wishing to obtain these mandates, or those who have reached these posts, share a rigorous and idealised vision of the functioning of the Boards and demand a model based on "sustainable governance" that is better adapted to the challenges which Boards face in our corporate world of upheaval. These women are potential "engines" for change.