Northwest Energy Efficiency Alliance (NEEA) directs an energy codes program, the objective of which is to influence a sustained market change through the development, adoption, and implementation of increasingly stringent energy codes in residential and commercial construction. This report presents the findings of a formal evaluation of this program. The evaluation framework used in this study is called a Market Progress Evaluation Report (MPER). This MPER was designed to evaluate the program’s progress in achieving its goals and provide recommendations to improve program performance moving forward. The focus of this MPER was on codes efforts undertaken since 2011 in NEEA’s region (in the states of Washington, Oregon, Idaho and Montana). Key research objectives of the MPER were to conduct reviews of: the program logic model; cost effectiveness assumptions used to estimate program influence; program progress achieved; and effectiveness of processes implemented. The evaluation found that NEEA’s codes program has made a significant contribution to the Northwest region through its support of energy code development and adoption, implementation, and compliance. The report’s recommendations for improvement include improved training assessment and timing.