This dissertation advances a new theory of normative transformation. It explains 'norm change' when previously prohibited practices become widespread and institutionalised, but without the obvious rise or fall of any single specific norm covering them. Three prominent cases, all in the recent history of US counter-terrorism and defence policies, offer an empirical puzzle this theory solves: the emergence of a targeted killing programme, the use of torture during interrogations, and the employment of armed private military and security contractors. In these cases, there has been no obvious demise of a given norm-against assassination, torture, or mercenarism-but it is clear that something changed the once-impermissible into an entrenched practice. To specify the causal processes underlying these cases, I shift the focus of analysis from 'norms' to 'normative configurations': unfolding relational arrangements of practices establishing values, principles, and rules. Drawing on pragmatist and relational sociology, I propose that normative configurations transform via three mechanisms, driven by innovative practitioner attempts to cope with new strategic and ethical pressures-by creative problem-solving. The first is convention reorientation, a change in the regulations and standards that define a given action. The second is technological revision, a change in the means by which an action proceeds. The third is network synthesis, a change in the relationships or organisational structures that grant and circumscribe authority. By tracing how these mechanisms worked in the three cases, I find that prohibitions on assassination, torture, and mercenarism still exist, but their referents changed due to new political and military pressures, along with the innovations that actors have developed to cope with them. This finding clarifies scholarly debates over whether/how the US's war on terrorism is counter-normative. More broadly, my approach contributes to the literature on international norms and practices. It dereifies 'norms' into their ontological constituents, enabling a granular, agency-centric look at how actors and institutions transform as a result of creative action. It thus widens scholarly discussions of norms to admit a broader range of sociological approaches, opening up the origins and effects of normativity to new kinds of theories.