Section 313 of the Emergency Planning and Community Right-to-Know Act (also known as Title III) of the Superfund Amendments and Reauthorization Act of 1986 (Public Law 99-499) requires EPA to establish a National Inventory of toxic chemical emissions from certain facilities. The final Toxic Chemical Release Form R and regulations for the 1987 reporting year were published in the Federal Register on February 16, 1988 (53 FR 4500-4554). The list of toxic chemicals subject to reporting consisted initially of chemicals listed for similar reporting purposes by the States of New Jersey and Maryland. There are over 300 chemicals and categories on these lists. The reporting requirement applies to owners and operators of facilities that have 10 or more full-time employees, that are in Standard Industrial Classification (SIC) codes 20 through 39 (i.e., manufacturing facilities) and that manufacture (including importing), process or otherwise use a listed toxic chemical in excess of specified threshold quantities. The law mandates that the data be made publicly available through a computer database. The online TRI file should appeal to a broad based user audience including industry, state and local environmental agencies, emergency planning committees, the Federal Government and other regulatory groups. Another important user group is likely to be concerned citizens who, on their own or through public interest groups and public libraries, can use TRI to ask questions about chemical releases in their communities.