In 2010, the International Organization for Standardization published ISO 26000: a standard to guide organisations in implementing social responsibility and contributing to sustainable development. ISO is a widely respected authority on standards worldwide, so their venture into this field was significant. But how much of a contribution can ISO 26000 make to sustainable development?~~This report looks at what has happened so far and what the potential could be. The paper argues that unlike some of the best-known ISO standards on other subjects, ISO 26000 does not address how to manage sustainable development issues in a systematic way. And it does not provide for independent certification of its application. This limits its appeal to many companies and makes it difficult to measure accurately its rate of adoption and impact. However, the worldwide reach of ISO and its members – the 162 National Standards Bodies – together with the commitment of key governments, including the Chinese, is likely to ensure that the standard is actively promoted.~~While it is too early to measure its specific impacts, one key contribution of ISO 26000 has been to legitimise a broader definition of organisational responsibility — particularly for companies. The standard broadens the concept of organisational governance to include sustainable development and the interests of stakeholders, not just shareholders. This is important, because stakeholder empowerment is a central component of social sustainability and social justice. ISO 26000 is a standard that will have worldwide significance, and its impact should be carefully monitored.