1,4-Dioxane is an emerging contaminant that is most commonly known for its use as a stabilizer in some chlorinated solvents. As an environmental contaminant, 1,4-dioxane has been the focus of regulation and treatment since the early 2000s and was immediately recognized as both difficult to quantify via conventional laboratory analyses and difficult to treat using conventional techniques for chlorinated solvents. 1,4-Dioxane is most commonly known for its historical use as a stabilizer in the chlorinated solvent 1,1,1-trichloroethane (TCA). The presence of 1,4-dioxane at chlorinated solvent sites continues to be a challenge due to the evolving and increasing regulation around 1,4-dioxane concentrations in environmental media, such as groundwater. Historically, groundwater remediation activities did not include investigation and treatment of 1,4-dioxane. The chapter provides information on the most relevant, applied, and/or developing treatment technologies that are specific to 1,4-dioxane treatment in groundwater.