The long-standing and multifaceted scientific cooperation between the Department of Soil Science and Engineering Geology of the Faculty of Geology at Moscow State University and the Department of Geotechnical Engineering of the Faculty of Mining and Geology at the University of Belgrade, their common understanding of engineering-geological problems, and their shared fundamental methodological principles concerning the justification, design, and construction of engineering structures created favorable conditions for a joint investigation of one of the most important problems in engineering geology: “Landslides, Formation, and Stability of High Slopes in Complex Geological Structures.” Faculty members, researchers, graduate students, and undergraduate students from the engineering geology departments of Moscow State University and the University of Belgrade carried out field and laboratory investigations in their respective countries according to a common research program. The work was supervised by the scientific editors of this monograph, Professor G. S. Zolotarev and Professor M. Janić. During the first stage of the contemporary research program, methodological issues were selected from among the many aspects of the problem under study. These issues were considered the most important and were supported by sufficient material for the synthesis of field, experimental, and theoretical investigations. The monograph consists of six chapters and an appendix containing sample engineering-geological maps at various scales, legends, definitions of concepts, and related materials. The selection of study objects and regions involving landslides, collapses, and other slope processes was determined by the research programs of the participating departments. Researchers from the Engineering Geology Department of Moscow State University primarily summarized investigations carried out in mountainous slope regions of southern parts of the Soviet Union, including the Eastern Carpathians, the Black Sea coasts of southern Crimea and the Caucasus, and the northwestern and southwestern sectors of the Tien Shan. From among the numerous and diverse landslide-prone regions of Yugoslavia, the slopes of the Đerdap Reservoir, the Visočica River Valley, the Lim River Valley along the newly constructed Belgrade-Bar railway, and the deep open-pit mine slopes of Macedonia and eastern Serbia were selected as case studies. Since Serbian legislation required geological investigations and established standards for their justification and economic efficiency, a special Section 5 was added to Chapter One for the regulation and planning of engineering-geological investigations. This monograph summarizes the research experience accumulated by the two university departments in the fields of landslides and high-slope stability. It was prepared collectively by a number of researchers whose names are listed in the table of contents. Professor B. Kulonjić, Professor D. Stefanović, and Professor M. Marković of the University of Belgrade, together with Associate Professor I. Šukin, P. Lokin, and D. Boženović, participated in discussions of the manuscript and provided valuable recommendations, many of which were incorporated into the book. V. S. Fedoseiko rendered substantial assistance in preparing the materials for Chapter Two, several other sections, and the engineering-geological map examples. Research on cartographic methods and the preparation of engineering-geological maps, illustrations, and other graphics were carried out by A. F. Berngof. O. L. Vinogradova, L. A. Derkach, and A. F. Gerasimova participated in the final preparation of the manuscript for publication. The authors express their sincere gratitude to Academician E. M. Sergeyev, Head of the Department of Soil Science and Engineering Geology at Moscow State University, as well as to the reviewers of the monograph, G. A. Golodkovskaya and I. O. Tikhvinsky, for their assistance and valuable advice. The authors recognize that this book may still contain shortcomings. They and the editors will be grateful for any comments and suggestions from readers. Correspondence may be addressed to the Department of Engineering Geology at Moscow State University or the Department of Geotechnical Engineering at the University of Belgrade.