Throughout history, women from all over the world have come together for diverse and often contradictory purposes in informal networks, or as participants in men's organizations, or even more or less covertly. However, in Britain and Ireland at least, it is only in the past two centuries that they have in significant numbers banded together openly, formally, separately and autonomously. They have done so for a variety of reasons: to further a political cause, to improve social relations, to improve their understanding of the world or to acquire particular skills, to share a leisure or cultural interest, to further an occupational or professional interest, for solidarity with women of similar persuasions, to distinguish themselves from other women, and sometimes for good fellowship or just to have fun. This dictionary is the first attempt to identify systematically the large and heterogeneous group of such organzations, from women abolitionists and Chartists through social workers, nurses, suffragists and sexual reformers to women pilots, journalists and cricketers. The work brings together over 500 entities on a wide variety of societies, associations, clubs, unions and other professional, social and political bodies organized by women or for women covering the period 1825 to 1960. This work should be of interest to social historians and specialists in women's history.