This article seeks to consider the substantive content, monitoring and enforcement issues, and legal implications arising out of such calls for ‘international corporate social responsibility’ (ICSR). It begins with a brief overview of the reasons why investor responsibilities have become a major strand in the debates on the future development of international investment law. It then considers what is meant by the term ‘international corporate social responsibility’. It also discusses the major legal developments to date in the field of standard setting for corporate responsibilities, followed by a brief overview of monitoring and enforcement issues. The relationship between treaty-based standards and national regulatory standards is addressed. This article concludes by considering what the implications of these developments might be for the evolution of international investment agreements (IIAs).