Gender mainstreaming (GM) commits implementing organizations to eradicate the gender bias in their policy and actions. However, disappointing outcomes observed in multiple examinations of GM implementation have shown that the processes involved in the eradication of gender bias have been under theorized. Applying the gender knowledge concept in combination with insights from science and technology studies and the sociology of knowledge, this article deconstructs some of the dynamics involved in the perpetuation of gender bias and the efforts of the Directorate General for Research in the European Commission to displace it. The findings illustrate the resources, collective dynamics, and epistemic barriers involved in the implementation of GM and show the promise of the gender knowledge concept for a deeper analysis of the reproduction of state gender bias, and possibilities for its eradication.