The volume contains the complete proceedings of the Symposium on Advanced Experimental Techniques in the Mechanics of Materials, held in San Antonio, Texas, September 9-11, 1970. The papers address four general problem areas: surface defect characterization, internal defect structure, surface deformation and strain, and stress state and fracture. The techniques discussed include magnetic methods, electron para-magnetic resonance, Mossbauer spectroscopy, the Barkhausen phenomenon, acoustic emission, laser interferometry and holography, ultrasonics, and internal friction measurements. The full text of each of these papers is included. Concluding the volume are the informal remarks of each of the session chairmen, made at the close of the symposium, wherein each chairman attempted to critique briefly the approaches presented in the papers in his session, and put them in a more general perspective. (Author Modified Abstract).