Transparency will here be used to denote any kind of measure that publicizes information about an institution’s behavior, such as monitoring, reporting, or simply responding to inquiries. Commonly recognized as a desirable institutional value for everything from corporations to governments, transparency in recent years has developed from a buzzword into a substantive policy tool, particularly in efforts to make transnational actors more socially and environmentally responsible. But merely exposing the behavior of an actor is not the same as holding an actor accountable; while knowledge is the first step toward enforcement, further policy measures must be enacted. This paper examines transparency mechanisms as a means of understanding how transparency succeeds and fails at establishing accountability.