BackgroundSince the passage of Proposition 99, California's comprehensive tobacco control programme has benefited from a localised policy adoption process that allows for the innovation and diffusion of strong local tobacco control policies throughout the state.MethodsThe policy adoption continuum is described in the context of California's smoke-free workplace movement, and the influence of policy-driven tobacco control initiatives on social norms, behaviour and the public's health was examined.ResultsThe Smoke-free California policy adoption continuum reflects a general approach for policy innovation and diffusion that builds social acceptance and influences social norms, while minimising unintended consequences and creating best practices in tobacco control. California's local smoke-free workplace policies have reduced secondhand smoke exposure and supported attitude and behaviour changes. The effects of local policy adoption led to the nation's first statewide smoke-free workplace law.ConclusionsProposition 99 created an unprecedented tobacco control infrastructure that supported local policy innovation and diffusion to influence social norms and behaviours. Tobacco control policy efforts should address campaign challenges, oppose pre-emption and confront tobacco industry influence. Advocates must be cautious of pursuing a statewide policy prematurely, as it may result in a weak and/or pre-emptive policy that can stymie local policy efforts and prolong the adoption of a meaningful statewide policy.