Nature-Based Solutions and Water Security: An Action Agenda for the 21st Century presents an action agenda for natural infrastructure on topics of standards and principles, technical evaluation and design tools, capacity building and innovative finance. Chapters introduce the topic and concepts of natural infrastructure, or nature-based solutions (NBS) and water security, with important background on the urgency of the global water crisis and the role that NBS can, and should play, in addressing this crisis. Sections also present the community of practice’s collective thinking on a prioritized action agenda to guide more rapid progress in mainstreaming NBS. With contributions from global authors, including key individuals and organizations active in developing NBS solutions, users will also find important conclusions and recommendations, thus presenting a collaboratively developed, consensus roadmap to scaling NBS. Covers all issues of water security and natural infrastructures Presents a comprehensive state of synthesis, providing readers with a solid grounding in the field of natural infrastructures and water security Includes a fully workable and intuitive roadmap for action that is presented as a guide to the most important actions for practitioners, research questions for academics, and information on promising careers for students entering the field