The Zero-Emission Vehicle (ZEV) mandate, one of the most daring environmental policies related to transportation, was implemented in September, 1990, by the California Air Resources Board (CARB). It originally required that, starting in 1998, 2% of the in-state new light duty vehicle sales of major automakers had no emissions of criteria pollutants. The required ZEV percentage would be increased to 5% in 2001 and to 10% in 2003. CARB organized biennial reviews of the programs, to elicit stakeholder participation and monitor the evolution of the program. Through this review schedule, the program underwent several revisions resulting from intense policy debates. This dissertation research is concerned with the study of the policy process over the ZEV mandate, from its conception, through its inception, and the biennial reviews, until 2004. The study is structured as three core chapters. The first chapter studies the origin of the ZEV mandate, trying to understand the conditions that favored and the factors that resulted in its implementation. To guide the study in this chapter, I use the Multiple Streams theoretical framework. The second chapter presents an empirical study of the policy process during the biennial reviews. This study aims at understanding the dynamics of policy change and coalition stability, identifying the policy dimensions that dominated the debate over time. I use the Advocacy Coalition Framework to frame the study in this chapter theoretically. The third core chapter presents a theoretical study of the strategic policy behavior of the main actors in the policy process. I develop a game-theoretical model of an environmental regulator (CARB) that needs to set emission standards in the presence of multiple industry players (automakers), who in turn need to decide on their level of compliance in the presence of a competitor. The model presented improves over previous published work in the subject. The results of these studies yield numerous conclusions with both theoretical and practical implications. I find that Multiple Streams is useful to understand the origin of the ZEV mandate, while I identify and/or confirm arguments by other scholars about significant limitations in the framework. Through the analysis of the public testimonies given by stakeholders at the biennial reviews, I identify the policy areas of major concern at different points in time along the policy process. I also identify the policy positions of each stakeholder and obtain estimates of the groups of stakeholders with similar policy beliefs (belief coalitions.) I find that these belief coalitions show some stability over time, though less than what was found by previous studies. One of the major conclusions from the model of strategic behavior is that the competitiveness of the auto industry tends to preclude collusion. The regulator may use this industry competitiveness to its advantage and achieve higher social benefits.