What role can corporate codes of conduct play in monitoring compliance with international labour standards and improving working conditions in global supply chains? Addressing this question, the authors first summarize the results of research on factory audits of working conditions in 800 of Nike's suppliers in 51 countries and two intensive case studies. They then discuss how the codes fit into the broader array of institutions, policies and practices aimed at regulating and improving working conditions, suggesting an evolutionary and complementary approach to regulating working conditions in global supply chains. They outline additional research and institutional innovations needed to test these ideas.