The straightforward motion and stress analysis that has been so successful in the design of airframes has seldom been applied to equipment and is not too effective there. On the other hand, the conventional application of vibration specifications to sub‐assemblies leaves the resonances within the equipment very loosely controlled, so that the attainment of reliability is dependent primarily on testing the entire equipment and making design changes until the results are satisfactory. Furthermore, information on resonances of standard parts such as vacuum tubes and relays is not readily available. There is an urgent need for rules for controlling configuration and resonance in the course of design, so as to achieve something close to an optimum in the least possible time and decrease any amount of calculation, testing, or redesign required thereafter. Test procedures can be modified to assist such a design approach. Some complication results from consideration of mechanical impedance relationships, but not enough to prevent improvement of the development process.