This report proposes a taxonomy of policy design features for agri-environmental payment schemes, with a focus on those features that are conducive to policy cost-effectiveness. An application of the taxonomy to all agri-environmental payment schemes in six countries (Argentina, Australia, Estonia, Finland, Korea, and Portugal) reveals that more than 70% of 85 agri-environmental payment schemes have some of these key design features, including establishment of baselines; rates based on estimated or actual implementation costs; inspections and penalties; contract flexibility; and technical assistance. That said, at least 80% of the schemes could be improved, including by: use of cost-effectiveness criteria for selecting recipients; moving from supporting the adoption of specific practices to focusing on achievement of environmental outcomes; more regular policy evaluations; and comprehensive collection of information on policy characteristics. An in-depth application of the taxonomy to Korea illustrates the potential of this taxonomy for country policy monitoring and evaluation purposes.