This article examines the position of women within the modernization processes of British trade unions, based on the first analysis to date of projects funded under the British government's Trade Union Modernisation Fund. The focus of the article on the Trade Union Modernisation Fund provides unique insights into the relatively underexplored 'inner workings' of unions, and allows an examination of the types of modernization projects that may advance women's interests within unions and the types of challenges such initiatives face. The projects suggested that reflection and learning around women's interests and equality agendas were taking place, along with a degree of mainstreaming and embedding activity within union structures. However, projects had to face not only deeply entrenched constraints, but also a new set of challenges raised by the process of modernization itself.