Extensive studies of the microstructure of deposited films establish that grain boundary migration is a ubiquitous process in the development of microstructure and frequently the key process in the formation of a preferred orientation. This conclusion is supported by the interpretation of observations of the structure and orientation of films as a function of substrate temperature and post deposition annealing. Epitaxial deposits can result from oriented nucleation or selective growth processes. On amorphous substrates the anisotropy of the interfacial energies of the deposit results in a fiber texture at temperatures when grain growth occurs either during deposition or in a post-deposition anneal.