Natural gas is poised to enter a golden age, but this future hinges critically on the successful development of the world's vast unconventional gas resources. North American experience shows unconventional gas - notably shale gas - can be exploited economically. Many countries are lining up to emulate this success. But some governments are hesitant, or even actively opposed. They are responding to public concerns that production might involve unacceptable environmental and social damage. This report, in the World Energy Outlook series, treats these aspirations and anxieties with equal seriousness. It features two new cases: a Golden Rules Case, in which the highest practicable standards are adopted, gaining industry a 'social licence to operate'; and its counterpart, in which the tide turns against unconventional gas as constraints prove too difficult to overcome.