During the last week of September 1968, ESRIN (the European Space Research Institute) held the ESRIN-ESLAB Symposium on 'Low-Frequency Waves and Irregularities in the Ionosphere' in Frascati, near Rome. The symposium was attended by about 60 participants, including speakers from most of the ESRO member states, the U.S.A., the U.S.S.R., and Peru. The main topics covered were: (a) observations of ionospheric irregularities by radar scattering, (b) scintillations of satellite signals, (c) geomagnetic micropulsations, and (d) whistlers. Both theoretical and observational aspects were treated. In addition, laboratory results on low-frequency waves in plasmas were discussed, emphasis being given to their possible relevance to low-frequency ionospheric phenomena. Finally, a brief presentation (not included in these proceedings) of the ESRO rocket and satellite program was given by Dr. Pedersen of ESLAB. The symposium provided an exchange of information among workers in closely related fields. It was also valuable in bringing together people whose experience is predominantly in ionospheric observations with others whose field of interest is mainly in plasma physics (theoretical or laboratory) - a combination that seemed particularly appropriate to ESRIN's program and functions.