As a component of natural attenuation or in combination with engineered efforts, microbial degradation is often a crucial contributor to in situ remediation efforts at chloroethene contaminated landfills. Laboratory and field investigations have identified a number of mechanisms for anaerobic microbial degradation of chloroethenes and the conditions under which these mechanisms are favored. Although widely observed to occur in anaerobic environments, reductive dechlorination is rarely complete and generally results in accumulation of toxic compounds (DCE and VC). However, recent laboratory and field evidence indicates that indigenous microorganisms also can catalyze a net oxidation of DCE or VC to CO₂ via distinct degradation pathways that are strongly effected by the in situ redox conditions. These findings indicate that the microbial ecology of chloroethene contaminants in the environment is diverse and that a comprehensive understanding of the anaerobic oxidative degradation pathways and the circumstances under which they occur is necessary to effectively incorporate microbial degradation as a remedial component.