The Fourth Symposium (International) on Detonation is a continuation of a series of U.S. Navy sponsored meetings held at irregular intervals. The first, called 'Conference on the Chemistry and Physics of Detonation,' was sponsored by the Office of Naval Research and was held at the Navy Department, Washington, D.C. on January 11 and 12, 1951. It was a classified conference, but the printed proceedings have since been declassified. The 'Second ONR Symposium on Detonation' was held in Washington, D.C. on February 9, 10, 11, 1955. Preprints of this meeting were issued by the Office of Naval Research in two volumes; one classified, one unclassified. The 'Third Symposium on Detonation,' cosponsored by the Naval Ordnance Laboratory and Office of Naval Research was held at the James Forrestal Research Center, Princeton University on September 26, 27, 28, 1960. Preprints were made available by ONR in three volumes: ONR Symposium Report ACR-52, Volumes land 2 (Unclassified) and Volume 3 (Classified). This symposium was the first to restrict discussion to condensed phase detonations and related hydrodynamic, thermodynamic, and solid state problems.