There is tremendous potential to achieve energy and greenhouse gas reductions in the U.S. building stock. Today, U.S. policymakers are turning their attention to existing buildings, where opportunities for greater energy efficiency are abundant but fraught with barriers that continue to severely impede progress. This paper examines how mandatory rating and disclosure policies can help overcome barriers and achieve real progress. The paper also presents a policy framework, based on best practices in current policies, that maximizes the market transformation potential of rating and disclosure policy.