Editors' Summary: TSCA provides EPA with broad authority to address potential hazards posed by the manufacture, processing, distribution in commerce, use, and disposal of chemical substances and mixtures. In this first of a three-part series, the authors begin a detailed examination of the statute and regulatory program. They review the origins, objectives, and key components of TSCA, and then analyze TSCA's scope -- focusing particularly on definitional issues and exclusions. The authors next describe the TSCA Inventory of chemical substances manufactured or processed in the United States, including provisions for confidentiality, corrections, and updates to the inventory. Next, the authors review EPA's implementation of the premanufacture and significant new use notification provisions of TSCA § 5. In the final section of this initial installment of the three-part Article, they discuss the scope and application of the various exemptions from the premanufacture notice requirement.