This volume contains the papers presented at the First Mexico-U.S.A. Symposium on Materials Sciences and Engineering held in Ixtapa, Guerrero, Mexico, during Septem ber 24-27, 1991. The conference was conceived with the primary objective of increas ing the close ties between scientists and engineers in both Mexico and the U.S. with an interest in materials. The conference itself would have not taken place without the drive, determination and technical knowledge of John K. Tien of the University of Texas at Austin and of Francisco Mejia Lira of the Universidad de San Luis Potosi. This book is dedicated to their memory. The event brought together materials scientists and engineers with interests in a broad range of subjects in the processing, characterization and properties of advanced materials. Several papers were dedicated to structural materials ranging from ferrous alloys to intemetallics, ceramics and composites. The presentation covered properties, processing, and factors that control their use, such as fatigue and corrosion. Other materials and properties were also explored by U.S. and Mexican participants. Sev eral papers dealt with the characterization and properties of magnetics, optical and superconductor materials, nanostructured materials, as well as with computational and theoretical aspects likely to impact future materials research and development.