This book is intended for students of agricultural science, ecology, environmental sciences, and rural development, researchers and scientists in agricultural development agencies, and practitioners of agricultural development in government extension programs, development agencies, and NGOs. There is an emphasis on developing country situations, and on smallholder production systems. This second edition has been significantly enhanced by the inclusion of two new chapters (on Sustainable Agricultural Intensification and Climate Change), and the updating of all chapters to reflect new evidence and new directions in agroecology and farming systems. Each chapter is written by experts in their topic, with both academic and field experience, providing a synthetic and holistic overview of agroecology applications to transforming farming systems and supporting rural innovation that include technical, social, economic, institutional, and political components. The book is divided into four sections: the first section, Reinventing Farming Systems, introduces farming systems and the principles of agroecology, rural livelihoods, sustainable intensification, and sustainability. The second section, Resources for Agricultural Development, explores low-input technology, soil ecology, and nutrient flows, participatory plant breeding, and the role of livestock in farming systems. Section three, Context for Sustainable Agricultural Development, deepens understanding about inequalities in development (particularly gender inequality), the nature and spread of innovation in agriculture, supporting agriculture through outreach programs, and how agriculture is being, and will be, affected by climate change. The final section, Tying It All Together, takes a hard look at where we are now in terms of nutrition, wealth, and stability, and suggests a way forward. Rural innovation and building capacity to improve agricultural systems are themes interwoven throughout, which we hope that you enjoy learning about through this brand new edition of the book.