The third Advanced Study Institute (ASI) on Techniques and Concepts of High Energy Physics was held at the Hotel on the Cay, in the scenic harbor of Christiansted, St. Croix, U. S. Virgin Islands. Christiansted was the site of the first ASI, and it was certainly a delight to return there again. As in the previous ASI's, the aim was to bring together a small group of promising young experimenters and several outstanding senior scholars in experimental and theoretical high energy physics in order to learn about the latest developments in the field and to strengthen contacts among scientists from different countries and different backgrounds. The institute was both a great scientific and a great social success; much of this was due to the beautiful setting and to the dedication of the Hotel management of Ray Boudreau and Hurchell Greenaway and their excellent staff. The primary support for the meeting was once again provided by the Scientific Affairs Division of NATO. The ASI was cosponsored by the U. S. Department of Energy, by Fermilab, by the National Science Found ation, and by the University of Rochester. A special contribution from the Oliver S. and Jennie R. Donaldson Charitable Trust provided an important degree of flexibility, as well as support for worthy students from developing nations. As in the case of the previous ASI's, the scientific program was designed for advanced graduate students and recent PhD recipients in experimental particle physics.