The term “emerging contaminants” and its multiple variants has come to refer to unregulated compounds discovered in the environment that are also found to represent a potential threat to human and ecological receptors. Such contaminants create unique and considerable challenges as the push to address them typically outpaces the understanding of their toxicity, their need for regulation, their occurrence, and techniques for treating the environmental media they affect. With these challenges in mind, this handbook serves as a primer regarding the topic of emerging contaminants, with current and practical information to help support the goal of protection where they are encountered. Features Explores the definition, identification, and life cycle of emerging contaminants. Reviews current information on sources, toxicology, regulation, and new tools for characterization and treatment of: 1,4-Dioxane (mature in its emerging contaminant life cycle) Per- and polyfluoroalkyl substances (PFASs; a newer group of emerging contaminant) Hexavalent chromium (former emerging contaminant with evolving science) 1,2,3-Trichloropropane (progressing in its emerging contaminant life cycle) Provides thoughts on opportunities in managing emerging contaminants to help balance uncertainty, compress life cycle, and optimize outcomes.