This chapter explains how the pattern of impunity began to shift, and considers the ongoing challenges for prosecuting sexual and gender-based crimes under international law. It begins by defining the term 'sexual and gender-based crimes' and explaining the political significance of this term. It explains how sexual and gender-based crimes moved from the margins to the centre of international criminal law (ICL), due to the efforts of gender-sensitive prosecutors and judges in international and internationalised courts, along with women's rights activists and feminist legal scholars who called for greater attention to these crimes. The chapter discusses some long-standing gender biases and gaps in the legal framework that continue to inhibit the prosecution of sexual and gender-based crimes under international law. Although sexual and gender-based crimes are now widely recognised as among the most serious crimes of concern to the international community as a whole, the 'end of impunity' for these crimes under international law is still a long way off.