A sustainability index is an instrument used to measure the sustainability of a business across environmental and social factors. It provides non-financial data that can tell investors and stakeholders how a company is managed in a day-to-day setting and the importance that they place on environmental stewardship and social responsibility. There are dozens of different indexes that businesses can disclose to, each providing their own parameters and levels of credibility amongst the public. The Dow Jones Sustainability Index and FTSE4Good are the most popular in Europe, whilst the MSCI KLD 400 Social Index has a large representation in the US. Sustainability indexes are becoming increasingly important, not only as a measure of risk for investors, but also as a measure of environmental impact. In the face of aggravating climate change, it is paramount that businesses place sustainability at the forefront of their management. Being able to benchmark your company against others as well as being subject to pressures from the public is also a valuable driver of sustainability in business.