The first Guidebook: Toxic Substances Control Act, which by virtue of this publication has now become Volume 1 of this set was first published in July 1977, only 7 months after the Toxic Substances Control Act (TSCA) became effective. Since then, there have been a considerable number of more-or-less significant developments, not the least of which is a new Administration and a series of important new key Environmental Protection Agency personnel operating in a considerably reorganized, restaffed, and rebudgeted agency. While TSCA implementation may not have proceeded as far as some had been predicting in 1977, there nevertheless have been a considerable number of important regulatory, policy, enforcement, economic, scientific, and technical developments.