Globalization critics argue that international trade spurs a race to the bottom among national environmental standards. ISO 14001 is the most widely adopted voluntary environmental regulation which encourages firms to take environmental action beyond what domestic government regulations require. Drawing on a panel study of 108 countries over seven years, we investigate conditions under which trade linkages can encourage ISO 14001 adoption, thereby countering environmental races to the bottom. We find that trade linkages encourage ISO 14001 adoption if countries' major export markets have adopted this voluntary regulation.