The inspiration for this sourcebook came from a 2014 meeting of researchers, practitioners and policy makers in Addis Ababa under the auspices of an event co-convened by the Global Water Initiative East Africa (GWI EA), the International Water Management Institute (IWMI) and the Water, Land and Ecosystems programme of the CG system. The event agreed there was a pressing need for greater regional consolidation of knowledge on improving water management for smallholder farmers. The meeting allowed participants the opportunity to explore how an emerging concept developed under GWI EA of Water-Smart Agriculture (WaSA) could support future policy attention to and investment in this critical area.  This collection of articles develops further the WaSA approach in East Africa, providing a starting point for thinking and inspiring future efforts.