The environmental impact of industrial agriculture is under close scrutiny, by Governments, concerned citizens, and farmers. This paper discusses the need to incorporate environmental factors in measures of farm performance, as part of the continuous review of long term sustainability. The concept of natural capital allows natural resources to be considered in similar ways to other assets of the farm business. It is suggested that soil quality criteria, selected to match the site characteristics and purpose of the landowner, be included in these measures, despite continuing disagreement about the concept and difficulties in its application. The intuitive appeal of a soil quality paradigm is the potential to integrate the many dimensions of sustainability, encouraging responsible land management. It is further suggested that soil structure is a key indicator of soil quality, and methods for its assessment are summarized.