New requirements of the society and demands imposed by the Common Agricultural Policy (CAP) reform have increased the complexity level required from farm management systems. New approaches for helping the farm management are needed to assure a successful production system that is friendly to our environment and able to provide high quality information management. Successful management of farm activities requires indeed the collection, storage and manipulations of a considerable amount of information. Farm enterprises are complex systems we need to model to facilitate knowledge capitalization, business process re-engineering and integration, change management and Information System (IS)design and integration. Enterprise Modelling Languages allow business requirements models to be defined. Such business models help to align the business strategy, the organization infrastructure and the IS infrastructure, but are rarely used in the agricultural sector. We then propose in this chapter to apply 3 Enterprise Modelling Languages from the industrial sector to farm enterprise. After a brief presentation of modelling languages diversity, we will present the three Enterprise Modelling Languages (IDEF0, GRAI Grid and AMS) and illustrate their application to farm enterprise thanks to case-studies. We will then discuss their usability and the interest of Enterprise Modelling Languages compared to other modelling languages (such as UML) presented in other chapters in this book.