Family background; University of Southern California preparatory school, A.B. in physics at Stanford University (1920). Return to graduate school at California Institute of Technology; studied with Robert Millikan. Dissertation topic on electron spin; influence of Paul Ehrenfest (1928). Contribution of Beno Gutenberg to the development of the Richter Magnitude Scale. Publication of seismological data from atomic bomb tests; collaboration with Japanese. Difficulties of earthquake prediction. History of governmental earthquake measurement. Certification of geologists and geophysicists in California; R's consulting work. Public policy issues of safety in building of construction and the artificial triggering of earthquakes; role of insurance companies. Admission of women and humanities education at Caltech. Recollections of R.C. Tolman, Harold Jeffreys, Lee DuBridge, and Harry Bateman. Harry Wood's leadership of the Seismological Laboratory of the Carnegie Institution; instrument innovations after Caltech takes over laboratory.