A methodology has been developed which can be used to assess the environmental performance of a farm. The computer-based system, known as EMA, utilises a checklist auditing process based on both quantitative and qualitative data and looks, holistically, at the farm assessing a wide range of farming activities including crop production, crop protection, resource and waste management, livestock husbandry and conservation. The system relies on the use of eco-ratings which are activity based performance indices derived by comparing actual farm practices with what is perceived to be site specific best practice. The system utilises a similar approach to that used in standard environmental management systems, such as ISO14001, by providing a scale for performance measurement to allow monitoring of improvements and progress, and to permit performance highs and lows to be identified. The system has recently under-gone piloting and evaluation in-house, on-farm and in collaboration with a major UK Retailer, Safeway Stores plc. This paper describes this process and presents the findings in the form of case studies. A brief description of the system is included for completeness.