In this paper we illustrate how policy analysis models can deepen our understanding of the challenges facing health promoters advocating for policy change. Specifically we describe the factors underpinning the adoption of Québec's Tobacco Act (1998) and the role played by actors from governmental public health agencies (GPHAs). Data were collected through interviews (n=39), newspapers articles (n=569) and documents (n > 200) from GPHAs, NGOs, the Québec National Assembly, and opponents to the legislative measures. Data collection and analysis were based on Sabatier and Jenkins-Smith's Advocacy Coalition Framework (1999) and Lemieux's theorization of coalition structuring (1998). We explain the adoption of the Act by: (1) the broad recognition within the policy elite of the main parameters of tobacco use (i.e. lethality, addictive properties, and legitimacy of governmental intervention), (2) the impacts of a series of events (e.g. cigarette contraband crisis) that enabled tobacco control advocates to influence public debates, and the governmental agenda, (3) the critical contribution of a coalition of GPHAs pooling resources to address both the sanitary and economic aspects of the legislation while countering the opposition's strategy, and (4) the failure of the opponents to present an unified voice on the definition of the tobacco policy. This study illustrates the merits of applying a policy-change model to grasp the complexity of the process. Our findings call for the development of permanent policy analysis capabilities within public health agencies and for a broader scrutiny of the non-health-related dimensions of policy debates.