Irrigated farming is central to meeting the world's food and fodder needs and will be even more important in delivering on food security and water sustainability development priorities in the future. High population growth, climate change, increasing socio-economic growth, and water stress are key drivers of change. Although irrigation covers only 6.5 percent of the total land used for agriculture, it supports production of forty percent of the world's food and fodder output, with a gross value of fifty-five percent of global agricultural produce. Improving irrigation performance is a priority strategy in addressing rural poverty and in mitigating climate -change impacts, especially for the most vulnerable. Investment in irrigation has seen renewed interest in the past decade, and irrigation and drainage (I and D) governance emerging as a key focus for improved performance. Institutional failures and poor irrigation performance have been blamed on low capacity, perverse incentives, misdirected policies, and weak implementation but these are only contributing factors. Investments in institutions of the past have aimed to fix the institutions, with a focus on form and on organizational structure. The central message of this resource book is that functions, processes, and related capabilities must be the priority focus of all irrigation institutional interventions.