Nanostructured materials have opened new avenues in various scientific fields and are providing novel opportunities in environmental science. The increased surface area-to-volume ratio of nanoparticles, quantum size effects, and the ability to tune surface properties through molecular modification make nanostructures ideal for many environmental remediation applications. We describe herein the fabrication of metal and semiconductor nanoparticles for environmental remediation applications, particularly in ground water. We then summarize literature reports of nanostructures specifically tailored for remediation of environmental contaminants including organohalides, trinitrotoluene, and phenols.