In the policies and practices of gender mainstreaming, gender itself is a contested concept. This article examines versions of gender mainstreaming in two countries, focusing on approaches we term the Canadian and Netherlands models. We show how different understandings of gender are attached to different reform approaches, and intimate how particular ways of conceptualising gender inhibit the efficacy of the mainstreaming strategy. In order to increase that effectiveness we suggest that gender mainstreaming models incorporate a view of gender as a verb rather than as a noun, so that the focus is on the processes of gendering rather than on the static category of ‘gender’. We make the argument that such a shift could: a) incorporate a feminist ontology of the body; b) align an understanding of gender as an unfinished process with the ways in which those who make and implement policy experience gender mainstreaming as always partial and incomplete.