Expectations are that the agricultural sector will have to expand the use of water for irrigation to meet rising food demand, given population and income growth. At the same time, the competition for water resources is growing in many regions. Increasing water productivity in agriculture is widely seen as a critical response to help address these challenges. Yet much of the public debate is vague on the meaning of agricultural water productivity—often emphasizing “more crop per drop” as if water were the only input that mattered—, and approaches for assessing and increasing water productivity are seldom addressed systematically. This paper discusses conceptual issues that should be kept in mind when assessing agricultural water productivity, and presents findings from what may be the first survey of the agricultural productivity and efficiency literature with regard to the explicit inclusion of water aspects in productivity and efficiency measurements. The survey includes studies applying single-factor productivity measures, total factor productivity indices, frontier models, and deductive models. A key finding is that most studies either incorporate field- and basin-level aspects but focus only on a single input (water), or they apply a multi-factor approach but do not tackle the basin-level aspects. It seems that no study on agricultural water productivity has yet presented an approach that accounts for multiple inputs and basin-level issues. However, deductive methods provide the flexibility to overcome some of the limitations of the other methods.