During the last several years, the nascent field of environmental biotechnology has advanced through the addition of specialized contaminant- degrading microorganisms that facilitate bioremediation. This process is termed bioaugmentation. Coupled with bioaugmentation has been the emergence of targeted molecular diagnostics to better engineer and manage the bioremediation process by accounting for the biological components of the contaminant attenuation process. The newly evolving paradigm is that these processes and techniques expand the options available to regulatory decision making, and thus affect contaminated-site closures. This "diagnostics and therapeutics" approach to the inventory of contaminated sites has gained traction from some federal agencies, as evidenced by significant funding initiatives that include field implementation. This paper focuses specifically on the use of bioaugmentation and molecular diagnostics in the bioremediation of chlorinated ethene-contaminated sites. We also describe...