This paper is a part of an ongoing research project focused on developing and testing a “modelling by design” approach for building system dynamics models to support both decision making and education purposes. To motivate the development and evaluation of the approach, we use multiple case-studies driven methodology. Our case studies are focused in the areas related to defense capability-based planning and analysis. In this paper, we outline the development approach, define the problem domain, and give an early glimpse on the modelling framework, and its key component