In addition to slenderness, today's female body must be firm with muscle tone. It must not, however, be muscular and the aim of this theoretical paper is to examine the resistance to female muscularity by focussing on the female bodybuilder. It will be revealed that even within a sport whose aim is to build muscle, female muscularity is resisted and that as women have become more muscular this resistance has become greater. It will be argued that this is because muscularity signifies masculinity and represents visible differences between women and men. This enables notions of masculinity to be validated and gender conventions reinforced. Because she challenges gender boundaries, the muscular woman must be resisted in order to maintain the patriarchal gender order.