The Blackfoot Reservoir volcanic field (BRVF), Idaho, USA, is a bimodal volcanic field that has hosted explosive silicic eruptions during at least two episodes, as recently as 58 ka. Using newly collected terrestrial and marine gravity data, two large negative anomalies (−16 mGal) are modeled as shallow (<1 km) laccoliths beneath a NE-trending alignment of BRVF rhyolite domes and tuff rings. Given the trade-off between density contrast and model volume, best-fit gravity inversion models yield a total intrusion volume of 50−120 km3; a density contrast of −600 kg m^-3 results in model intrusion volume of 63 km3. A distinctive network of 340°−360° trending faults lies directly above and on the margins of the mapped gravity anomalies. Most of these faults have 5−10 m throw; one has throw up to ∼50 m. We suggest that the emplacement of shallow laccoliths produced this fault zone and also created a ENE-trending fault set, indicating widespread ground deformation during intrusion emplacement. The intrusions and silicic domes are located 3−5 km E of a regional, 20 mGal step in gravity. We interpret this step in gravity as a change in the thickness of the Upper Precambrian to lowermost Cambrian quartzites in the Meade thrust sheet, part of the Idaho-Wyoming Thrust Belt. Silicic volcanism in the BRVF is a classic example of volcanotectonic interaction, influenced by regional structure and creating widespread deformation. Exogeneous and endogenous domes are numerous in the region. We suggest volcanic hazard assessments should account for potentially large-volume silicic eruptions in the future.