This study addresses the role, status, and identities of wage earning women within the trade union movement through the prism of 'labour feminism.' It considers the extent to which the idea that women should have the same opportunities as men, an idea which we now call feminism, informed working women's activism. How did women on the shop floor, on the picket lines, and in the union hall negotiate between a feminist position and trade union practice? I argue that trade union-based feminism, which I call 'labour feminism,' informed many women's activism on both sides of the Atlantic in the late nineteenth and early twentieth century.Labour feminism was not a coherent ideology, but was, at various moments, a practice and an agenda. Paying dues, attending meetings, or standing on the picket lines, rank and file women attempted to balance their trade union and gender identities. These women challenged contemporary gender roles as they articulated an active role for women in the labour movement. Those who became union leaders, whom we may call labour feminists, further developed this labour feminist position into an agenda, which the women's labour movement pursued. In both its informal state as a site of tension and negotiation and in its more formal state as a programme, labour feminism united the identities of 'woman' and 'worker' as it articulated the gender specific experiences, grievances, and demands of wage earning women within and via the labour movement.In practice, the labour feminist position was fluid and negotiable as women activists debated their role in the labour movement among themselves and with male unionists. Grounded in the experiences of garment workers, this study discusses this process of negotiation. It illustrates the tensions between rank and file labour feminists, those women who held official positions and formulated a labour feminist agenda, and male unionists as these women workers tried to put labour feminism into practice. It demonstrates that, despite the differences between the size, history, ethnic composition, and industrial base of Chicago and London, the commonalities in working women's experiences contributed to the construction of a transatlantic labour feminism.