Since the methodology used for compiling maps of mean suspended-sediment concentration has remained essentially unchanged, the author considers it unnecessary to describe it here in greater detail than was done in the present work. The concluding section points out the need to expand sediment-observation programs in regions where sediment-runoff processes remain insufficiently studied. Against the background of the extensive development of hydraulic-engineering projects in the Soviet Union, including hydropower construction, water-supply systems, and irrigation works in arid regions, design organizations required hydrological studies of river sediment runoff and its seasonal distribution throughout the year. In response to these needs, the Laboratory of Sediment and Water Chemistry of the State Hydrological Institute systematically organized and processed available materials during the previous two years in order to determine long-term average values of annual and monthly suspended-sediment concentrations and water turbidity. In the author's earlier publication, Suspended-Sediment Runoff of the Rivers of the USSR (Proceedings of the State Hydrological Institute, Vol. 20 (74), 1949), data were presented for 778 observation stations up to the years 1945-1946. The present work uses data available through and including 1952. During this period, the number of observation stations increased to 1,015, representing an increase of approximately 30%, while the duration of observations at existing stations also became longer. The increase in the number of stations and the extension of observation records made it possible to determine more accurately the long-term average characteristics of water discharge and sediment runoff. In addition, tabulated monthly mean values of suspended-sediment concentration and turbidity were provided for nearly all observation stations. Beyond the tabular data, the book includes large-scale detailed maps of mean river sediment concentrations for the European part of the USSR, the Caucasus, and Central Asia, as well as a comprehensive map covering the entire territory of the Soviet Union, including Siberia, the Far East, and Northern Kazakhstan. The boundaries of the various sediment-concentration zones are described in detail. In compiling these maps, local landscape characteristics and erosion conditions were taken into account.