The fifth Advanced Study Institute (ASI) on Techniques and Concepts of High Energy Physics was held again at the Hotel on the Cay, in the scenic harbor of Christiansted, St. Croix, U. S. Virgin Islands. The ASI brought together a total of 71 participants, from 17 different countries. It was another great success, due to the dedication of the inspiring lecturers, the exceptional study body, and, of course, the beautiful setting. The primary support for the meeting was 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 Foundation, 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 ca se of the previous ASI's, the scientific program was designed for advanced graduate students and recent PhD recipients in experimental particle physics. The present volume of lectures should complement the material published in the first four ASI's, and prove to be of value to a wider audience of physicists.