In this anthology, the editors want to review the first 12 years of European emissions trading, clarify its significance today and finally look ahead. To this end, they addressed renowned experts from science, business, politics, associations and organizations and asked for their views on the European emissions trading system (EU ETS). This book contains articles with a retrospective focus, some of which are very personal but extremely colourful, describing the exciting phase of the beginning from the direct perspective of the participants involved. With all its contributions, the book provides a comprehensive overview of the emergence, impact and further development of European emissions trading from these various perspectives. Many articles take up the negotiations and the results of the reform of the EU ETS for the fourth trading period. After the publication of the German edition in early 2018, there were many inquiries whether an English edition should be published, too. To learn more about the beginnings of the EU ETS in Germany especially from the perspective of different participants who were involved at the time would be helpful for many countries that want to take the path of emissions trading for carbon pricing. In addition to the visible successes of the ETS due to the growing number of planned and existing emissions trading systems, there have also been setbacks like in Australia, the USA and most recently in 2017 in the Canadian state of Ontario due to the absence or loss of political majorities and social support. The latter underlines the importance of a broad social acceptance of the ETS from the outset for the creation of a robust, predictable and long-term functioning emissions trading system. Germany's experience with the EU ETS can contribute to this.