As part of the worldwide effort to create an international earthquake data bank, the seismology archive of the California Institute of Technology (Caltech) has been organized, labeled, described, and microfilmed. It includes a wide variety of original records, documents, and printed materials relating to local and distant earthquakes. The single largest and most complex component of the task has been the preparation and microfilming of Caltech's vast collection of original seismograms. The original proposal envisioned a modest project in which a selected number of seismographic records at Caltech could be made more generally available to the scientific community. These single-copy records are stored at Kresge Laboratory and comprise thousands of individual photographic sheets, each 30×92 cm. In the end, we microfilmed both the Pasadena station records and those written at the six original stations in the Caltech network. This task got underway in June 1981 and was completed in January 1985. In the course of the project, the staff sorted, arranged, inventoried, copied, and refiled more than 276,000 records written between January 10, 1923 and December 31, 1962. The microfilm edition of the earthquake records at the Seismological Laboratory at Pasadena and at auxiliary stations at Mount Wilson, Riverside, Santa Barbara, La Jolla, Tinemaha, and Haiwee (the latter two in the Owens Valley) consists of 461 reels of film. The film archive is cataloged and available to researchers in Caltech's Millikan Library in Pasadena, at the U.S. Geological Survey in Menlo Park, Calif, and at the World Data Center (National Oceanic and Atmospheric Administration) in Boulder, Colo.