The ISEE-1 and ISEE-2 plasma wave investigation is designed to provide basic information on wave-particle interactions in the earth's magnetosphere and in the solar wind. The ISEE-1 plasma wave instrument uses three electric dipole antennas with lengths of 215, 73.5, and 0.61 m for electric-field measurements, and a triaxial search coil antenna for magnetic-field measurements. The ISEE-2 plasma wave instrument uses two electric dipoles with lengths of 30 and 0.61 m for electric-field measurements, and a single-axis search coil antenna for magnetic-field measurements. The ISEE-1 plasma wave instrumentation provides a comprehensive determination of wave characteristics over a broad frequency range, including high-frequency resolution spectrum scans, simultaneous high-time resolution electric- and magnetic-frequency-spectrum measurements, wave normal and Poynting flux measurements, and wide-band waveform measurements. The basic frequency range of the ISEE-1 measurements is 5.62 Hz-311 kHz, although wide-band waveform measurements can be made in selected frequency ranges up to 2.0 MHz using a special long baseline interferometer mode of operation. The ISEE-2 plasma wave instrumentation consists of a 16-channel spectrum analyzer covering the frequency range from 5.62 Hz to 31.1 kHz and a wide-band waveform receiver with the capability of making waveform measurements in selected frequency ranges up to 2.0 MHz.