Soil trafficability studies have shown that the strength of a soil is of major importance to vehicle mobility and varies principally with soil moisture; therefore, a means of predicting moisture content of a soil is essential to the forecasting of soil trafficability. The U.S. Army Engineer Waterways Experiment Station (WES) soil-moisture prediction method for United States soils was applied to sites in Colombia to determine whether the method was applicable for the prediction of moisture content of tropical soils. Data were collected at four prediction development sites in the subhumid climate of the 'Sabana de Bogota' located in the Andean Mountain ranges of Colombia. Changes in soil-moisture content, soil density, and soil strength with changes in weather conditions were investigated periodically for one year. These data were analyzed and used to predict daily soil-moisture content and to establish the relation between soil-moisture content and soil strength. The results show that the WES soil-moisture prediction method is applicable to prediction of soil-moisture content at the four sites in Colombia. Data were of sufficient quantity to establish soil-moisture depletion curves for each site but not of sufficient quantity to establish accretion relations. Relations were established between soil-moisture content and soil strength at all sites. Trafficability of the soils tested, as indicated by rating cone index, was good even when the soils were at maximum moisture content. Basic data and photographs for each test site are included. (Author).