This chapter provides a brief overview of permeable reactive barrier (PRB) technologies for groundwater remediation. It provides a selection of references covering the now extensive literature in the field of PRB groundwater remediation technologies. The risks that are posed to human health and to the environment by exposure to groundwater contamination are well recognized by regulatory bodies, owners of potentially contaminated sites, the local community, and the public at large. Groundwater contamination is now well recognized as an integral component of contaminated sites and its assessment and remediation can pose significant technical and financial challenges. The fate and transport of contaminants through soil to groundwater is influenced by many variables such as properties of the contaminant itself, soil conditions, and climatic factors. Pump-and-treat systems have been used for more than 20 years in the remediation of groundwater contamination.