The dynamic mechanical properties of rubberlike materials have been briefly reviewed. The value of a mounting composed of a low‐ and a high‐damping rubber in parallel is in this way made apparent. Expressions have been derived from which the ability of the so‐called parallel mounting to isolate vibration from any nonrigid foundation may be determined, if the mechanical impedance of the foundation is known.One‐ and two‐stage mounting systems have been considered. To compare their performance, the mechanical impedance of a damped beam has been employed to simulate the behavior of a nonrigid foundation. It is shown that the parallel mounting suppresses resonant motion at the natural frequencies of the foundation and the mounting systems with similar effectiveness to the high‐damping rubber, yet provides the greater isolation at other frequencies. The isolation afforded by the mounting is, in fact, often comparable to that which the low‐damping rubber affords.