In 2008, on the occasion of the “Grenelle de l’Environnement” Conference, France set itself the objective of reducing pesticide use by half within ten years. In order to answer the question of the authorities as to the feasibility of reducing pesticide use in French agriculture and reaching the target fixed by the “Grenelle de l’Environnement”, the INRA and the Ministries for Agriculture and Ecology launched the ECOPHYTO R&D project. We show here the results of research carried out within that study. A significant reduction in pesticide use requires major changes in farming practices. In order to analyse the impacts of such changes in the French arable crop sector, which represents 68% of pesticide use in France, a mathematical programming model was made. It studies the combinations of farming techniques which could achieve various levels of reduction in pesticide use and assesses the impact these changes could have on farm income and production. The results show that a 30% reduction in pesticide use could be achieved by changing the techniques used and without any major fall in production or margin (at 2006 prices). However, the 50% objective would lead to much greater falls in production and would require growth in the use of systems that are currently little used, such as integrated production and organic farming.