The Fourth Geodesy/Earth and Ocean Physics (GEOP) Research Conference was held on August 16 and 17, 1973, at the University of Colorado, Boulder. It was attended by about 65 persons. John Apel, general chairman, opened the conference, followed by Richard H. Rapp of the Ohio State University, who delivered the keynote address. The keynote address in its entirety is printed elsewhere in this issue. This address and the following summaries of the sessions constitute a report on this conference.