The course Physical Geography of the USSR, in terms of its scope, content, and method of presentation, was designed for senior students of geography departments at state universities and teacher-training institutes. The rich factual material included in the course is presented in accordance with the principal methodological principles and approaches of Soviet landscape geography. The fundamental regional unit is the geographical region, defined by the unity of its historical development and the distinctive combination of its modern geographical landscapes. The geological history of each geographical region prior to the Tertiary Period is outlined in broad terms, whereas the later periods, especially the Quaternary, are examined in greater detail from a paleogeographical perspective, describing ancient landscapes, their succession, and the ways in which different stages of historical development are reflected in the modern landscape. Each geographical region is considered both as a component of a larger whole, such as Western Siberia, Eastern Siberia, the Far East, or Central Asia, and as a unified geographical organism composed of a series of coordinated elements, including zones, subzones, districts, and landscapes. The author substantiates the boundaries of the various geographical regions and the principal patterns governing the distribution of their smaller taxonomic units. Since landscapes represent the most recent stage in the development of life within a particular area of the Earth's surface, the geographical description does not begin with the landscape but culminates in it. Landscapes are examined in terms of their development, geographical distribution, modern structure, seasonal dynamics, and their transformation for the purposes of the socialist economy. In describing flora and fauna, the author seeks to provide more detailed accounts of a limited number of landscape plants and animals that are particularly characteristic of the region under consideration and, wherever possible, to examine them within the context of biotic communities. Considerable attention is devoted to ecological factors, seasonal changes in vegetation, and the annual life cycles of animals. The author makes extensive use of factual material from related disciplines but does not seek to provide independent surveys of geology, geomorphology, climatology, plant geography, and other subjects when describing the individual components of regional units. These elements are regarded as inseparable parts of a unified geographical whole, and only information essential for constructing a landscape description is incorporated from the corresponding disciplines. The sequence and extent of treatment of the various components differ because the same factors play different roles in different geographical regions, and priority is given to those features most distinctive of a particular area. The abundance of factual material and the need for maximum conciseness of presentation, together with the desire not to disrupt the continuity of the text by repeatedly citing the names of numerous authors whose results were utilized, compelled the editor to avoid discussion of certain controversial issues and to adhere to his own views in dealing with fundamental geographical questions. Differences in the degree to which geographical regions have been studied, the desire to provide detailed descriptions of geographical objects of particular importance under conditions of socialist development, and the need to include important topics not adequately covered elsewhere in the geography curriculum, such as the study of permafrost, explain certain imbalances in the treatment of individual chapters of the book. Relatively few geographical names have been retained in the text itself; most have been transferred to the accompanying maps, which constitute an essential component of the geographical description. Most of these maps were compiled by the author on the basis of published sources and cartographic materials or adapted from existing maps in order to achieve the greatest possible clarity. This work was originally scheduled for publication in 1941, but it was destroyed during the heroic defense of Leningrad. In the years that followed, the author succeeded in restoring the text, making a number of additions and selecting new illustrative materials.