A seismic exploration of Mono Basin, California, was conducted by the U.S. Geological Survey in 1970 and 1971 to resolve two conflicting interpretations regarding the thickness of the basin fill and the nature of the boundaries of the structure. Interpretation of the seismic data obtained leads to the conclusions that the depth to basement in Mono Basin is 2--21/2 km and that the structural deformation along the boundaries of the basin was accomplished by a combination of warning and faulting. Thus the geophysical data suggest a structural model that lies between the two extremes of interpretation. Geologic, seismic, magnetic, and gravity data all indicate the presence of a pile of intrusive and extrusive volcanic rocks near the center of Mono Basin.