In recent years scholars have highlighted the public policy potential of using voluntary programs based on environmental management systems (EMS) to improve firms' environmental and regulatory performance. While firms receive some benefits for joining EMS-based voluntary programs, these incentives could be strengthened if governments mandated joining such programs as a precondition for participating in government procurement. While we support Arnold and Whitford's proposal to use public procurement eligibility criteria to induce firms to take environmentally progressive action, we have concerns about using any EMS or EMS-based voluntary program for these purposes. EMS-based programs must impose real requirements on firms and must have in place monitoring systems to ensure that such requirements are met. Only then will EMSprograms likely be effective as well as credible with stakeholders.