The concept of materiality is a bedrock feature of American securities law and regulation. It informs the way investors think, talk and transact, the way lawyers advise their clients, and the way legislators and regulators draft and enforce federal mandates. The working definition of materiality in the United States, which has served corporate America well for nearly nine decades, now finds itself facing significant pressures from a variety of sources. The European Union, the World Economic Forum, and other stakeholder- and EESG-oriented organizations are advocating for a broader definition and developing concepts of expanded materiality that go far beyond the traditional American approach in ways that threaten to undermine the usefulness of materiality as a guiding principle for disclosure.