There are a wide variety of modeling and simulation tools and technologies available for building lumped parameter physical models. Ultimately, engineers need to determine what tools they will use to pursue a model-based development process. Often, this is a daunting task for several reasons. First, many tools are domain or subsystem specific so while they are ideal in some contexts they are insufficient in others. In addition, different tool vendors have different strengths. It is not always easy to understand the advantages and disadvantages in order to choose the proper tool-chain.In this paper we distance ourselves from particular tools and take stock of the bigger picture. For this reason we avoid discussion of particular tools and instead catalog some of the more common physical modeling requirements across domains and subsystems as well as some of the interesting techniques being developed to facilitate robust physical modeling processes. To help ground the discussions with concrete examples (while avoiding discussions of specific tools), we will use examples developed in the Modelica modeling language (a vendor neutral modeling language). Ultimately, we hope this kind of analysis highlights some of the important requirements that support a “systems engineering” approach to physical model development.