This chapter looks at how indicators can be used to assess agricultural sustainability. Indicators are biophysical, economic and social attributes that can be measured and used to assess the condition and sustainability of the land from the farm to the regional level. Reliable indicators provide signals about the current status of natural resources and how they are likely to change. They can be used to confirm that current farming practices and land-use systems are effective in maintaining the resource base or economic status, identify problems and highlight potential risks. Indicators provide useful information for initiating change or deciding on future on-ground investments.