The SpaceX Vibration Isolation Clinic Team designed, built, and tested a one degree-of-freedom semi-actively controlled vibration isolation system, capable of being expanded to a six degree-of- freedom system. This system uses a magnetorheological damper, is scalable to a wide range of isolated masses, and is able to reduce vibration at the system’s natural frequencies to achieve a desired frequency response function. The system has the potential to be a light, inexpensive, and robust vibration isolation system.