In the early seventies, scientists in Israel and The Netherlands started a cooperative project on actual and potential production under semi-arid conditions. In Israel research concentrated on primary production of natural pastures and small grain crops, and on the associated secondary production of small ruminants. Most of the experimental work was carried out at the Migda Experimental Farm in the semi-desert of the northern Negev where the long term average annual rainfall is 250 mm. In The Netherlands existing facilities in Wageningen were used for measuring growth, photosynthesis and transpiration of Negev pasture plants and small grains under controlled conditions, both as individual plants and as simulated swards and crops. The joint research program was initiated by the late N.H. Tadmor and A. Dovrat from Israel and by C.T. de Wit and Th. Alberda from The Netherlands and conducted by various scientists from both countries, some of whom are among the authors of this book. The experimental results first served as a basis for the development, calibration and validation of simulation models of the growth and water use of pasture and crops. Subsequently, additional models were developed, allowing incorporation of socio-economic considerations, both at the farm and regional level, so harnessing the research results for analysis of regional development possibilities.