The French National Institute for Agricultural Research (INRA) has established an ambitious, multiscale, agricultural experimental infrastructure (the CA-SYS platform) as a collaboration between the Research Unit, Agroécologie (Dijon, eastern France), and the Experimental Research Unit, Domaine d’Epoisses (20 km next to Dijon). CA-SYS covers an area of 120 ha, and is divided into 47 fields, each of which has drainage and can be irrigated, and will be initiated in autumn 2018. The aims of CA-SYS are to: i) design and evaluate new agroecological systems; ii) study the transition from current farming systems towards these new agroecological systems, with goals that include agronomical performance, the evolution of farming practices and multi-performance criteria; iii) breed new varieties adapted to agroecological conditions, for example tolerance to stressors and the enhancement of beneficial plant-microbe interactions; iv) understand the ecological processes underlying the functioning of agroecological systems; and, v) develop and adapt experimental methods for studying agroecological systems. The originality of CA-SYS is that it is explicitly conceived for the development and evaluation of new agroecological systems across agriculturally realistic scales (Cordeau et al., 2015). An agroecological system will comprise a matrix of fields of one (or a few) cropping systems over a number of years. These fields will interact with adjacent semi-natural habitats in the landscape (woods, hedges, grass margin strips, flower strips). This spatio-temporal arrangement of fields and semi-natural habitats will be considered as a coherent strategy, implemented to meet specific goals. The agroecological systems tested across CA-SYS will consist of three zone of manipulation of the amount of adjacent semi-natural habitats available to enhance the natural enemies of pests and four cropping systems combining a large diversity of farming practices (no-till & cover crop basedsystems, tillage-based systems). CA-SYS has ambitious objectives, including an increase in the multi-performance of systems (profitability and productivity identical to neighbouring farmers over a 10 year-horizon, low environmental impact), by maximising the use of biological processes (biological control of pests, improving nitrogen cycling) and reducing the use of inputs (nitrogen, water, pesticides). CA-SYS is designed to allow research across four major themes: i) Breeding and evaluation of plant ideotypes for agroecological systems; ii) Understanding of plants/microbes (beneficial and pathogen) interactions in support of farm production goals using low levels of inputs; iii) The role of spatialtemporal structure and processes in functional biodiversity and biological control; and, iv) The design and evaluation of new agroecological systems. References : Cordeau, S., Deytieux, V., Lemanceau, P., Marget, P., 2015. Towards the establishment of an experimental research unit on Agroecology in France. Aspects of applied biology 128: Valuing Long-Term sites and Experiments for Agriculture and Ecology, 271-273.