International law has proved to be a highly dynamic legal order over time. However, dealing with change in international law is both analytically demanding and possibly normatively unsettling. The term ‘change’ regularly refers to distinct dimensions of change in relation to international law, ranging from alterations in its substantive content to the interplay between international law and its underlying social and physical reality. This conceptual heterogeneity has at times convoluted the consideration of the topic. Still, when conceptualizing international law as a process of continuous change over time, ‘practice’ emerges as the key normative vehicle enabling international law’s dynamism. The continuous normative responsiveness of international law to social reality – international law’s ‘facticity’ – actually operates as a defining characteristic of international law. The dynamic processes of change have regularly produced concerns about the stability of international law as a necessary precondition for international law’s capacity to provide a stable framework for social action in the international domain. At the same time, commentators have suggested that international law’s lawmaking tools may be inadequate for the realities of contemporary international relations due to the asynchrony between international law’s formal sources and social acceleration. However, both of these apprehensions seem overstated.