The paper presents a general theory of wave propagation through nonhomogeneous multiconductor systems. This theory shows that waves travelling in one direction through such a system do so independently of waves travelling in the opposite direction. The essential difference between homogeneous and nonhomogeneous systems is found to be that, in the former case, the propagation characteristics are the same in both directions, whereas in the latter case they are not. Methods for determining the forward and backward wave characteristics of a general nonhomogeous system are presented. The theory finds immediate application in the study of transient phenomena in powertransmission systems whenever nonhomogenity is involved. However, the theory is completely general, and may find useful applications in other areas.