This is the first book-length treatment of the political representation of women in countries with parliamentary systems based on the Westminster model. Written by a major international team of authors, this new study features twelve chapters on both new and established parliaments, including Australia, Canada, New Zealand and the United Kingdom. It tests the latest theories about women's political representation within Westminster style assemblies, and is organized into three key sections that: examine the extent to which the descriptive representation of women in the 'old' Westminster parliaments has progressed in recent years, and the factors which have enhanced or impeded development; explore the relationship between the numbers of women elected and the substantive representation of women - or the extent that women 'act for' women; and review the recent experiences of four 'new' Westminster parliaments (Northern Ireland, Scotland, Wales and Nunavut) and evaluate the political opportunities for women provided by the creation of new institutions. This new comparative study will be of great interest to students and researchers of legislative studies and of gender politics and gender studies.