Estimates of potential waterpower and historical data on waterpower developments in various parts of the world are assembled in this report. Salient characteristics of the period studied, 1955-62, include increased use of the underground powerhouse, multiple -purpose developments, and use of storage (including pumped storage) to increase the value of waterpower for peaking purposes. High-voltage long-distance transmission has been improved, especially in the United States, Sweden, and the U.S.S.R., and generating facilities tend to be larger than ever before. Asia leads the continents in total potential waterpower; Europe is first in use of waterpower. In rate of increase of waterpower installations and in percent of hydroelectric to total installations Africa is first among the continents. The 1955-62 period saw a great increase in per capita consumption of electric energy. Norway leads all countries with annual consumption of about 9,000 kwhr per capita. Waterpower development was carried on in a majority of the countries of the world and in most of them at an accelerated rate.