This publication, which highlights success stories and lessons learned, is aimed at a wide audience. The intent is to further raise awareness of the devastation that an environmental emergency can cause, and to promote advocacy and action in response. It also aims to highlight the strong need to integrate humanitarian and environmental action. Chapter 1 introduces the key players in the field of environmental emergencies and describes the development of the United Nations international response mechanism. The following three chapters highlight international responses to some of the many emergencies that have occurred as a result of industrial accidents, natural disasters and conflict situations over the past 15 years. Chapter 5 looks at some of the lessons that have been learned from environmental emergency response work, and how these have influenced changes in disaster response efforts and management. And the final chapter looks briefly at what is perhaps the greatest challenge affecting response and preparedness activities in the future: climate change.