In this paper, we provide a concept for the integration of the engineering and agronomic definitions of irrigation efficiency into the concept of water productivity. After water productivity has entered the water policy and research arena, there has been some confusion in its use and delineation from efficiency. We will therefore first make a clear differentiation between the terms, and then actually integrate the different kinds of efficiency into what we call agricultural water productivity. Agricultural water productivity then sets the boundaries within which efficiency indicates the smoothness of the water use process which itself is directed towards high agricultural water productivity. The latter denotes at which points a process has to be efficient in order to get the highest overall value out of water. Applying this system perspective of water productivity to agriculture allows going beyond yield as the only output from irrigation water use, but considers different outputs with differing values. The conceptualisation of agricultural Water productivity provides a sound basis for a harmonized application of irrigation and water use efficiency and water productivity to decision making.