Editors' Summary: Recent lawsuits by state and local governments, public interest organizations, and private citizens against electric companies, automobile companies, and lead paint manufacturers signify the reemergence of the common law as a powerful tool for protecting the environment. In this Article, Denise E. Antolini and Clifford L. Rechtschaffen provide a broad introduction to various common law theories that can be used to protect the environment, including trespass, nuisance, strict liability, and public trust. They conclude with a discussion of when and how environmental statutes preempt federal and state common law claims. [Editors' Note: This Article appears in the book Creative Common Law Strategies for Protecting the Environment, edited by Clifford Rechtschaffen and Denise Antolini, published in 2007 by ELI Press. The book can be ordered either by calling ELI at 800-433-5120 or logging on to the ELI website at http://www.eli.org.