This edited volume sets out to examine how the backlash against gender equality and women’s rights affects the aims and ambitions of the WPS agenda. Since the adoption of UN Security Council Resolution 1325 in 2000, the Women, Peace and Security (WPS) agenda has grown to form a comprehensive normative framework and body of knowledge. However, backsliding of women’s rights in the UN and beyond signals a potential reversal of an agenda that has steadily progressed and diffused globally for the past 30 years. Today, we see a backlash against liberal progressive norms, and support for women’s rights cannot be taken for granted as conservative and patriarchal norms gain ground within existing international and domestic normative structures. In this introductory chapter, we theorize and illustrate the interplay between norm development and regressive politics that aim to undo normative progress. The chapter presents an overview of research on the implementation and contestation of the WPS agenda, followed by a theoretical exploration of the concept of backlash. The chapter also asks what backlash against WPS norms might look like, and how resilient WPS norms might be. Finally, we outline the volume, summarize the contributions of each chapter to the study of the WPS agenda and conclude by emphasizing the volume’s overall theoretical and empirical contributions to the field.