This Review is about the significant contribution of women on boards and in senior management roles, and the proven performance value of their contributions in these capacities. The name and idea behind this Review came from a Toronto CFA Society conference earlier this year in which a number of presentations were titled "Gender Diversity". We would like to commend Sue Lemon, Toronto CFA Society CEO, who was the leader in organizing this conference. This Review summarizes a number of articles, including some from that conference, which support the case for women in these roles. We would also like to thank one very well-known Canadian board member - Eileen Mercier – a Fellowship Award recipient of the ICD, and long-time Chair of Ontario Teachers' Pension Plan Board, for her great contribution in helping me with this Review.