This publication is a collection of most of the papers presented at the Symposium on Characterization and Determination of Erosion Resistance, organized by Committee G02 on Erosion by Cavitation or Impingement in co-operation with the U. S. Office of Naval Research, at the Seventy-second Annual Meeting of the American Society for Testing and Materials held at Atlantic City, N. J., 22-27 June 1969. A Thiruvengadam, Hydronautics Inc., now at Catholic University of America, presided as chairman of the symposium, and F. J. Heyman, Westinghouse Electric Corp., presided as co-chairman of the symposium.