This chapter describes a new biodiversity index developed for the Tool of Agroecology Performance Evaluation (TAPE), a tool from the Food and Agriculture Organisation of the United Nations (FAO). The goal of TAPE is to assess the sustainable performance of farms. Since TAPE covers several sustainability dimensions, is applied internationally, and requires minimal data collection effort, developing a simple yet meaningful biodiversity index was a challenge. The new index is largely based on existing indicator frameworks, from which mainly indicators related to the farm’s structure and management were integrated, such as grazing intensity or pesticide use. The new biodiversity index was tested on 21 Swiss farms and compared with a more comprehensive method, showing satisfactory results. The biodiversity index has since been applied in other countries (e.g. Kenya) and can be adapted to suit the objectives of each project.