Geodetic observations, comprising Interferometric Synthetic Aperture Radar (InSAR), Global Positioning System (GPS), and precision leveling measurements, are used to infer volume change in the subsurface associated with the dynamics of the Yellowstone volcanic system. We focus primarily on the Yellowstone Caldera and its related magmatic, hydrothermal, and fault systems. It appears that known faults play a significant role in controlling crustal volume increases and decreases due to the migration of volcanic and hydrothermal fluids. For example, over 5 cm of subsidence from 1992 to 1995 is associated with source volume changes 6–10 km beneath the NW-trending Elephant Back fault zone and a north-trending fault cutting across the caldera. Furthermore, we are able to image an episode of fluid intrusion near the northern edge of the caldera. The intrusion is elongated in the north-south direction and is parallel to the north-trending volume decrease. The primary intrusion and related hydrothermal activity occurred between 1996 and 2000, though the volume changes appear to have continued, shallowed, and changed shape between 2000 and 2002. There is evidence that the intrusive activity influenced extensional faults to the north of the caldera.