The adoption of alternative fuel vehicles (AFVs) has been regarded as one of the most important strategies to address the issues of energy dependence, air quality, and, more recently, climate change. Despite decades of effort, we still face daunting challenges to promote wider acceptance of AFVs by the general public. More empirical analyses are needed to understand the technology adoption process associated with different market structures, the effectiveness of regulations and incentives, and the density of infrastructure adequate to reach sustainable commercial application. This paper compares the adoption of natural gas vehicles (NGVs) in eight countries: Argentina, Brazil, China, India, Italy, New Zealand, Pakistan, and the US. It examines the major policies aimed at promoting the use of NGVs, instruments for implementing those policies and targeting likely stakeholders, and a range of factors that influence the adoption of NGVs. The findings in this paper should be applicable to other AFVs.