The most important climate agreement in history, the Paris Agreement on Climate Change represents the commitment of the nations of the world to address and curb climate change. Signed in December 2015, it will come into force on the 4th November, and efforts toward fulfilling its ambitious goals are already under way. This text combines a comprehensive legal appraisal and critique of the new Agreement with a practical and structured commentary to all its Articles. Part I discusses the general context for the Paris Agreement, detailing the scientific, political, and social drivers behind it, providing an overview of the pre-existing regime, and tracking the history of the negotiations. It examines the evolution of key concepts such as common but differentiated responsibilities, and analyses the legal form of the Agreement and the nature of its provisions. Part II comprises individual chapters on each Article of the Agreement, with detailed commentary of the provisions which highlights central aspects from the negotiating history and the legal nature of the obligations. It describes the institutional arrangements and considerations for national implementation, providing practical advice and prospects for future development. Part III reflects on the Paris Agreement as a whole: its strengths and weaknesses, its potential for further development, and its relationship with other areas of public international law and governance.