This is the Summary Report of the ‘‘High Intensity EM Waves’’ working group at the 3rd International Workshop on Advanced Accelerator Concepts held June 14–20, 1992 in Port Jefferson, Long Island, New York. The requirements for future linear colliders with regard to microwave amplifiers is delineated in Section I along with key parameters that allow for the determination of the present status of each research effort that was discussed at the conference. The present status of amplifiers with beam energies less than 800 keV are summarized in Section II. In Section III, we summarize the status of the more non‐traditional schemes associated with the two‐beam concept, in which the energy of the microwave‐generating electron beam is much greater than 1 MeV.