In spite of being a multi-billion-dollar undertaking fundamentally reshaping the lives of people around the world, UN peacekeeping has only recently started to attract scholarly attention among a broader audience. While the evolution of norms and practices in other international organizations, such as the World Bank, the IMF, or the UNHCR, has been extensively analyzed, the transformation of peacekeeping operations has been no less significant.

This journal has, of course, been at the spear tip of publishing scholarly investigations into UN peacekeeping, and has in recent years received more competition from other journals covering international relations more generally. We think this is a good thing, as it reflects the importance of peacekeeping as a central instrument in the international peace and security toolbox, and a useful empirical starting point to tease out a more fine-grained theoretical understanding of continuity and change in international relations.

The four articles in this special section focus on norms in UN peacekeeping (gender, impartiality, human rights, and environmentalism) and how they are implemented in practice. They look at the evolution of these norms over time; take an explicit theoretical perspective (feminist institutionalism, norm contestation, and securitization); and report the results of original field research in Rwanda, South Sudan, and New York UN headquarters. The articles present a coherent narrative because they all look at practices either explicitly or implicitly, often at the mundane everyday level among troops or UN staff. But the focus on everyday experiences should not betray their theoretical importance: each of the articles uses this empirical material to better understand and theorize international relations. Georgina Holmes provides us with micro-study of norm implementation on the individual level with her bottom-up study of training of female military peacekeepers.¹ Marion Laurence reveals how legitimating practices are changing in tandem with the changing understanding of the impartiality norm.² Emily Paddon Rhoads analyzes impartiality as a composite norm and unpacks its procedural and substantive dimensions to reveal how human rights and protection are being privileged to the detriment of a more political understanding of impartiality.³ Lucile Maertens is forcing us to examine the causal chain of securitization theory by showing how security is shaped by environmentalization.⁴

Finally, the articles also have significant policy implications: questioning the need for more female peacekeepers if they are trained according to militarized gender protection norms and relegated to spaces and tasks that are perceived safe; contemplating the consequences of reframing or even moving away from impartiality; assessing the impact of the human rights agenda on the UN’s ability to provide good offices and play a central and impartial mediation role; and considering the tendency of the environmentalization of security which also leads to the securitization of the environment. Together, the articles contribute to the literature on the evolution of international organizations; on norms and their contestation, institutionalization, and implementation; and on the role of practices in giving meaning to norms.