This Article highlights the role of advocates in pushing government to step up to the challenges of reducing greenhouse gas (GHG) emissions and remaining steadfast through continued policy enforcement. The authors, who participated in the development of the Massachusetts Global Warming Solutions Act, provide insights regarding climate legislation, regulation, and litigation in a state committed to addressing climate change. They conclude by sharing lessons learned and recommendations for how state governments can shape future climate laws to take into account the necessary near-term and longer-term GHG emission reductions, and establish mandates that maximize enforceability.