CWA method. The formulation of a theoretical basis for the eva- luacion of insitu coal through the use of geophysi- cal logs is outlined. This involved the development of an approach to the interpretation of resistivity in environments having multiple conductive and non- conductive components. Utilizing this approach and other conventional interpretation techniques, a program was developed yielding accurate determina- tion of the insitu percentages of coal, water and ash for the evaluation of coal deposits. Basic in- formation obtained from the CWA program can be uti- lized in numerous aspects gf total mine planning.