This article offers an analysis of seven articles from the Review of Radical Political Economics’ series “What ‘Radical’ Means in the 21st Century.” Without reference to feminism, the authors’ definitions of “radical” hinge critically on insight from feminist radical political economy. Instead of feminist radical political economy fitting under a broader body of political economy that coheres around radicalism, it is in feminist insight that radical political economy finds roots: according to the series’ authors, it is what makes radical political economy radical. Yet although the Union for Radical Political Economics hosted the development of the building blocks of feminist theory in economics between 1968 and 1991, feminist contributions remain largely unacknowledged. I offer strategies for repositioning feminism not as a side project but as a critical source of insight for radical political economy. JEL Classification: B54, B51, B24