Almost every country has formulated its Nationally Determined Contribution to the global response to climate change. These national climate action plans were key to the landmark adoption of the 2015 Paris Agreement. They will also be central to its implementation - even if, taken together, current plans are insufficient to meet the aims of the Paris Agreement. Every five years, countries update their NDCs to demonstrate increased ambition. But while essential, ambition alone is not enough. This book shows that to be able to realize their climate ambition, countries also need to enhance the effectiveness of their plans and policies. Enhancing effectiveness involves improving the transparency, coherence and implementability of their NDCs. To ramp up ambition and effectiveness, future NDCs must build on and learn from experience. Based on a detailed analysis of the first round of NDCs by some of the world's most knowledgeable climate policy experts, this book offers critical insights relevant to mitigation, adaptation and means of implementation. The book also discusses key elements of the Paris Agreement and broader climate policy, including the Enhanced Transparency Framework and the Paris Committee on Capacity Building, as well as considerations of equity and development. It is a must-read for researchers, policymakers, practitioners, and civil-society experts working on climate policy. The chapters in this book were originally published as a special issue of the Climate Policy .