The book explores how the same international norms can have radically different effects in different national and local contexts, or within particular organizations, and in turn how this variation can have profound effects on people's lives. How do international norms change and adapt at implementation? Which actors and structures matter for shaping whether implementation actually takes place, and on whose terms? And what lessons can we derive from this for both International Relations theory and for international public policy-makers? Collectively, the chapters explore these themes by looking at three different types of norms - treaty norms, principle norms, and policy norms - across policy fields that include refugees, internal displacement, crimes against humanity, the use of mercenaries, humanitarian assistance, aid transparency, civilian protection, and the responsibility to protect.