Alternative fuel vehicles (AFVs) are an important component of a sustainable approach to clean, healthy air and efficient use of energy. Increased use of AFVs has the potential to lower emissions and reduce U.S. dependence on foreign oil. Targeting government fleets for AFV conversion can be cost-effective because government fleet purchase and replacement behavior is often politically motivated. For example, the Energy Policy Act of 1992 (EPAct) requires federal and state agencies and alternative fuel providers purchase a percentage of light-duty AFVs each year. There are knowledge gaps in understanding the adoption and diffusion of sustainable AFV technologies in government fleets . Specifically, research is needed to (1) articulate a defensible measure of sustainable practice at the fleet level, (2) examine the social networks that link fleet organizations, and (3) determine the policy and organizational factors that constrain the decision environment of adopters.