The second Advanced Study Institute (ASI) on Techniques and Concepts of High Energy Physics was held at the Roaring Brook Resort at Lake George, New York. As in the case of the first ASI, our aim was to bring together a small group of promising young ex­ perimenters and several outstanding senior scholars in high energy physics in order to learn about the latest trends in the field and develop stronger contacts among scientists from different countries and different backgrounds. The setting at Roaring Brook was particularly congenial and the staff, under the direction of George Green, was both friendly and efficient. The ASI was supported mainly through funds provided by the Scientific Affairs Division of NATO. It was cosponsored by the U. S. Department of Energy, Fermilab, the National Science Founda­ tion and the University of Rochester. A special grant from the Oliver S. and Jennie R. Donaldson Charitable Trust provided a valuable degree of flexibility for supporting worthy students. The scientific program of this ASI was, once again, designed primarily for advanced graduate students and recent Ph.D recipients in experimental particle physics. I believe, however, that the contents of the present volume will prove useful to an even wider audience of physicists.