Subvolume A of two subvolumes on Diffusion in Semi-conductors and Non-Metallic Solids consists of a comprehensive and critical compilation of data for the following materials and properties: diffusion in silicon, germanium and their alloys, diffusion in compound semiconductors, diffusion in silicides, chemical diffusion in bulk inhomogeneous semiconductors, grain-boundary and dislocation diffusion in semiconductors and silicides and surface diffusion on semiconductors. Although most of the silicides are not semiconducting, this chapter is included here because a number of them have become integrated in the Si technology and because they were not covered in the previous volume III/26 on diffusion in metallic substances. Subvolume A contains a CD-ROM.