To facilitate engineering studies of tropical soils, and particularly their airphoto interpretation, a classification system is proposed which covers major groups of soils peculiar to the tropics, soils common in both tropical and subtropical regions, and soils common in all climates. The origin and formation of tropical soils and their relation to climate, parent material, topography, and age are reviewed. The physical and chemical characteristics, and engineering problems of each of the major soil groups are examined. A method of airphoto interpretation by direct recognition of soil features, and by inference gained from observation of soil-forming factors and circumstances is presented. Air and ground photographs from Central and South America, tropical Africa, Southeast and South Asia, and Australia are included to illustrate a cross section of the major soil groups in the tropics. Recommendations are made for further study toward refining the airphoto interpretation of the major groups and subgroups of tropical soils, in addition to the supplementary use of other remote sensing devices. (Author).Prescott9 J, A. and Pendleton, R. L. (1952), Laterite and Lateritic Soils, Commonwealth Bureau of Soil Science Technical ... Stone, K. H. (1961), World Air Photo Coverage, 1960, Photogrammetric Engineering, vl7, n2, pp. 214-227, April, Symposium, Tropical Soil Resources (1963), Soil Science, v95, n4 , April. TAMS ... Memo n3-331, Rept.6, vi and v2, Forecasting Traff icability of Soils, Airphoto Approach.