AbstractResearchers and practitioners in system dynamics usually follow a trial‐and‐error process to design new policy decisions. They mainly use influence diagrams for this purpose. However, these diagrams portray the direction of influence but not its strength. Therefore, the process of policy design becomes time‐consuming, especially for beginners and those working with insufficient computer facilities. This paper presents an alternative approach for policy design using modal control theory. Policy variables are treated as control variables by delinking them from other variables. This generally leads to greatly simplified models that are free from many nonlin‐earities. Provided that this reduced system is linear and controllable, it is possible to synthetically generate control policies by modal control theory to ensure any prescribed degree of stability. These theoretical control policies then can be used to design realistic policy decisions. This approach has been used in a test