This paper explores a novel equality mainstreaming tool in EU spending—the “ex-ante conditionality”—as introduced in the 2014–2020 European Structural and Investment Funds. It shows that conditionality is a response to the modest achievements of prior equality-mainstreaming action in spending, but that its current legal construct and operation risk propagating similar shortcomings. The article concludes by emphasizing the importance of mainstreaming as a crucial tool for progressive achievement of equality and social justice in the EU, and highlights four essential elements to be addressed for a successful equality mainstreaming policy in EU spending.