The transfer of information regarding workplace exposure to toxic substances has received considerable public attention. It is clear that workers need an accurate picture of the nature and extent of likely chemical exposures in order to decide whether to enter or remain in a particular workplace. Workers also need to have ledge regarding past or current exposures in order to be alert to the onset of occupational disease. Regulatory agencies must have timely access to such information if they are to devise effective strategies to reduce disease and death from occupational exposures to toxic substances. Accordingly, laws designed to step up this flow of information have recently been promulgated at the federal, state, and local levels. Indeed, the right to know has become a political battleground in many states and communities, and has been the subject of intensive organizing efforts by business, labor, and citizen-action groups. Not surprisingly, this flurry of political activity has generated a degree of confusion. What is meant by the right to know? Who has the right? How is it exercised? What information is within its scope? These questions touch on a relatively complicated area of the law, and their resolution demands attention to the specific provisions of a number of different statutes, ordinances, and regulations. But this is also an area of the law that is amenable to a relatively simple conceptual framework. The purpose of this article is to lay out that framework in practical terms. In addition, we offer a general road map through the current body of law governing toxics information transfer in the workplace. (See Ref. 2 for a more detailed discussion of the issues raised here.)