It is well known that the artificial systems that enable modern society to function—such as automobiles, aircraft, printing systems, the electrical grid, and medical devices, among others—are becoming more and more complex. This complexity often exceeds the cognitive abilities of a single human designer or even that of sophisticated product development organizations to comprehend. This talk will review typical measures of complexity for cyber-physical systems and focus in particular on graph energy as a key measure (independent of the degree of abstraction of the system) for quantifying structural complexity. Several invariants such as the P-point, where complexity exceeds a critical threshold, and the importance of the average nodal degree of 6 will be discussed as crucial foundations for a more proactive approach to complexity management in the development of cyber-physical systems and the emerging first law of systems engineering: conservation of complexity. The speaker will advocate the establishment of “complexity” budgets similar to mass and power budgets in science and engineering.