["Environmental Policy and Governance, EarlyView. ", "\nABSTRACT\nThe interest in putting a price on carbon emissions is increasing in pace with the urgency of climate change. In this article we compare the adoption of one such policy instrument, carbon taxation, in the cases of Sweden and Mexico. We use a theoretical framework that focuses on economic and environmental factors influencing the policy process via distinct policy areas, as well as the mechanisms these factors operate through and their impact on agency. Despite the differences between the countries, the adoption of carbon taxes in these two cases was shaped by surprisingly similar factors. In both cases ideational change allowed for framing carbon taxes in environmental and economic terms, which eased coalition‐building between economic and environmental actors once broad fiscal reforms changed power dynamics and opened windows of opportunity for policy adoption. These findings contain lessons regarding interacting factors shaping policy adoption, including the critical importance of actors exploiting synergies.\n"]