Disordered materials offer new and unexpected insights into the structure of solids and the ways charge carriers move and interact with their environment. The first part of this review volume presents new results and ideas in the subject dealing with the local bonding structure in amorphous and vitreous semiconductors. These include the local bonding structure in chalcogenide glasses containing metal atoms, the interaction of local vibrational modes with their local bonding environment, and new models for the H-bonding configurations.The second part is devoted to questions of low temperature hopping transport and recombination of photocarriers in disordered semiconductors as a function of frequency and at high electric fields. The reviews by leading experts offer different insights and attempt to address problems from the various angles.