Nothing provokes a debate like UN sanctions; there seems to be an instant polarizing quality to the topic. In the post-Cold War era, have become a key security council tool in responding to international peace and security situations. Sanctions are applied not just to stop hostilities, but to improve governance, protect natural resources, promote democracy, and decry abhorrent practices such as the use of child soldiers or the incitement to violence and hatred. The sanctions decade of the 1990s witnessed an 86-fold increase in the number of UN regimes employed, making the security council's most important and most used coercive tool.1 Twenty-three mandatory regimes have been created since 1990; 12 are currently active. The council is very likely, indeed encouraged, to reach for as an alternate to force in dealing with an international crises.Increased use, however, does not necessarily translate into increased success or effectiveness. For many analysts, UN are ineffective and generate too many complications and unintended consequences. The sheer number and long duration of regimes threaten to overwhelm the UN system's ability to monitor or manage them. With the advent of targeted sanctions, the full weight of the council, once reserved for states, is now aimed at individuals who do not necessarily have recourse to judicial remedy. And the jury is out on the degree to which any of these regimes are ultimately able to achieve their goals. These factors are all cited as evidence by those who argue that the heyday of is over, or that it should be.The vastly expanded UN experience in using as an international peace and security tool, and the resulting divergence of opinions on their utility, prompted the director of the Centre for International Relations at Queen's University, Charles Pentland, and the Canada Research Chair in international relations and security studies at the Royal Military College of Canada, Jane Boulden, to host two international workshops on the subject of UN sanctions. The first workshop, held in 2007, focused on the humanitarian impacts of sanctions. The second workshop, held in 2008, took a step back from the literature to explore what was new about UN and what could be learned from the considerable experience now under the UN's belt.The overall goal was twofold: first, to establish the current state of play in UN in the wake of the council's consistent, frequent, and increasingly innovative use of sanctions; and second, to consider how to evaluate that experience as we look ahead to future UN security council action. This issue of International Journal, dedicated to UN sanctions, tackles these two broad areas in a series of articles penned by international experts who participated in the workshops.In many ways the council's apparent wholesale embrace of as a tool mirrors its experience with peace operations. As with peace operations, the council's post-Cold War willingness, even desire, to address a wide range of international peace and security issues resulted in a wealth of new experiences and a concomitant, if often inadvertent, innovative bent. And as with peace operations, the council's efforts generated a whole host of unanticipated outcomes and unintended consequences, prompting new rounds of adjustment and retrenchment, lessons learned and applied.The result is a complex picture in which the council has developed a range of tools to address a spectrum of international peace and security issues. Indeed, rather than a single tool, can now more properly be seen as a whole drawer in the security council toolbox, in which a wide range of tools are available for use in a variety of situations against a variety of targets, including nonstate actors as well as states. This is in sharp contrast to the Cold War and the early post-Cold War period when the council mainly used as a blunt-force mechanism against a state as a whole. …