I n the early 1970s, barely a trace of what is today a rapidly growing infrastructure on corporate responsibility existed. Overall, the responsibility infrastructure encompasses a variety of different institutions that place pressures on companies for greater accountability, responsibility, transparency, and sustainability. Some of these institutions, like social investment, an emergent responsibility assurance infrastructure, business associations, and internal responsibility management approaches, are market based, in that they rely onmarketmechanisms. Others are based in civil society, including multi-stakeholder dialogues and collaborations, non-governmental organizations (NGOs), activists, interest groups, watchdogs, and ratings and rankings. In parts of the world, legislative and regulatory action is also beginning to focus, in particular, on issues of disclosure and transparency around ESG – environmental, social, and governance – aspects of firms. Below, I explore how a select group of individuals called difference makers used pragmatic vision and social entrepreneurship to build some of the pioneering institutions of the responsibility assurance framework now emerging. This framework is part of a much more extensive network of emerging institutions around corporate responsibility. It encompasses: (1) standards, codes, and principles that businesses are increasingly expected to live up to; (2) credible monitoring, verification, and certification systems to provide assurance that what is stated by companies is what is actually being done; and (3) generally accepted reporting standards comparable to financial reporting standards, but focused on non-financial or ESG matters. This infrastructure has created both new visibility for issues of corporate responsibility and also numerous responses and increasingly proactive momentum among companies, particularly multinational corporations who are in the limelight, around ESG issues. Although there are many individuals whose work could be highlighted, space constraints focus this manuscript on the work of only a few of the many difference makers. SEEDS OF RESPONS IB I L I TY ASSURANCE