Objectives. To identify unintended health effects of California’s controversial cap-and-trade regulations and establish health-promoting policy recommendations, we performed a health impact assessment., Methods. We used literature reviews, public data, and local health surveys to qualitatively assess potential health risks and benefits related to changes in employment and income, energy costs, effects of emission offset projects, and cobenefits from the allocation of program revenue. We examined case studies from various communities to find existing social, economic, and environmental health conditions., Results. We found that policy implementation will minimally impact job creation (< 0.1% change) and that health effects from job sector shifts are unlikely. Fuel prices may increase (0%–11%), and minor negative health effects could accrue for some low-income households., Conclusions. Offset projects would likely benefit environmental health, but more research is needed. Allocating some program revenue for climate change adaptation and mitigation would have substantial health benefits. Health impact assessment is a useful tool for health agencies to engage in policy discussions that typically fall outside public health. Our results can inform emission reduction strategies and cap-and-trade policy at the federal level.