This paper analyses the effects of the main determinants of international aggregate agricultural supply. We propose a new model that captures the farmers’ expectations through the storage approach, instead of using Nerlove's basic model. As an innovation, we add the effects of efficiency and technological change directly, thus achieving a more powerful and informative estimation than with the usual dynamic model. Moreover, we consider the effect of climate and construct a sowing and harvesting calendar for each country and each crop to measure the supply more precisely. We also analyze the effects of agricultural prices and their volatility, of commercial policy and of changes in inventories on the suppliers’ decisions. Finally, we examine the differences in these determinants depending on the level of development of the countries. [EconLit citations: Q11, Q16, Q18].