The European Union (EU) was an influential voice in advocating the adoption of gender mainstreaming by the 4th United Nations World Conference on Women in Beijing in 1995. Since then gender mainstreaming has become a central policy plank of gender justice globally, but progress has been variable and modest. This paper examines the unfolding of gender mainstreaming in the EU, which was one of the early adopters as reflected by its commitment to gender mainstreaming in 1996. The objective is to identify patterns that may have implications for gender justice on a broader scale. The lenses are the European Employment Strategy dating from 1997 and targeted gender equality initiatives dating from the Community Framework on Gender Equality (2001–2005). Drawing on documentary analysis of these sources constraints on moving form aspiration to policy practice and outcome are identified. These are intensified by the multilevel structure of decision-making in the EU, which means that commitments agreed at the EU level are not pursed with the same fervour by all member states. But constraints are inherent in gender mainstreaming because of the contested and vague nature of the concept, the context of cross-cutting inequalities and the structural basis of these inequalities.