There is good evidence that improvements in crop productively have come from increases in yield rather than from decreases in total water use. In irrigated agriculture, there are increasing attempts to decrease the unproductive losses of water from storage, through distribution systems and onto fields. This chapter defines the meaning and implications of increased water productivity, and then systematically considers the limits and opportunities for improvement. Water productivity is considered in the context of both rain-dependent (often called ‘dryland’) and irrigated agricultural production. The chapter acknowledges that many agricultural systems have animals as part of food and fibre production, and argues that efforts to increase water productivity need to consider whole agricultural systems.