Monitoring and Evaluation (M&E) canbe defined as the systematic and objective measurement andassessment of progress and performance of an intervention. Acomprehensive system documents activities, outcomes, andimpacts; promotes transparency and accountability; andfacilitates continuous learning. The system should alsoevolve, expand, and improve over time to adapt to changingneeds, priorities, capabilities and available data. Climatepolicy evaluation uses data to answer specific questionsabout the implementation, outcomes, and effects of policy orrelated issues. A theory-based approach facilitatesevaluation of the entire implementation process. Through thedevelopment of indicators for each step in the process, itis possible to not only learn which policies are successfulor not, but also why they succeeded or failed and how theycan be improved.