Using the controlled-source electromagnetic technique, resistivity soundings were obtained at 49 •locations around the summit caldera and upper rift zones of Kilauea volcano. Each sounding consisted of vector measurements of the magnetic field induced by a large-moment horizontal loop current source at discrete frequencies between 0.04 and 8 Hz. The source-to-sensor distances ranged from 2.5 to 13 km. The data have been computer-inverted to produce a best-fitting horizontally layered earth model. Although each sounding's interpretation is different in detail, the volcano’s structure appears simple and can be represented by four, subhorizontal layers. The surface layer is highly resistive and coincid.es with. the dry, basaltic overburden. At a depth of 500 to 1000 m, resistivities decrease abruptly to between 30 and 50 ohm-m, marking the top of the water-saturated zone. The third layer occurs between 2 and 3 km depth and has a resistivity of less than 10 ohm-m and a total conductance of about 200 mhos. This layer is underlain everywhere by highly resistive rock to a depth of at least 6 km, the estimated limit of penetration by this study. Pockets of low resistivity (less than 20 ohm--m) occur irregularly within the high-resistivity basement. Because of its widespread occurrence, 'the shallower conductive layer (layer 3) is probably water-saturated rock at high, temperature; however, the possibility of thin, intruded sills of magma contributing to the low resistivities cannot be refuted, The pockets of low resistivity within layer 4 occur at a depth of 5 km and are believed to be magma chamber 2 to 3 km deeper than models derived from earthquake hypocenter location and surface deformation studies. / ill