In 2016, Mayor Martin J. Walsh signed the Metro Boston Climate Mitigation Commitment, pledging to make Boston, Massachusetts carbon neutral by 2050. The Carbon Free Boston summary report quantifies the most effective combinations of strategies to reduce greenhouse gas emissions across our energy, buildings, transportation, and waste sectors. The report is intended to provide an analytical framework for the City of Boston and its key stakeholders to use in making choices about which specific strategies and policies to pursue to achieve the goal of being carbon neutral by 2050.