System principles differ from systems engineering principles differ in important ways (Watson 2018a). System principles address the behavior and properties of all kinds of systems, looking at the scientific basis for a system and characterizing this basis in a system context via specialized instances of a general set of system principles. SE principles are a specialized and contextualized instantiation of systems principles that address the approach to the realization, use, and retirement of systems. SE principles build on systems principles that are general for all kinds of systems (Rousseau, 2018a) and for all kinds of human activity systems (Senge 1990, Calvo-Amodio & Rousseau 2019). Hence, system principles guide the definition and application of SE processes – a strong systems engineer must be the master of both system principles and SE principles.