A discussion is given of the scanning-electron-diffraction technique. The importance of energy analysis of the diffracted beams in both reflection and transmission diffraction is emphasized. Details are given of the results of experiments in which intensity patterns are recorded while metal films are being deposited onto room-temperature carbon substrates inside the electron-diffraction system. Intensity profiles across the Debye-Scherrer rings have been obtained at 10- to 20-sec intervals, corresponding typically to 10-Å increments in film thickness; thus, diffraction patterns corresponding to the earliest stages of growth could be recorded. Representative specimens were examined by electron microscopy. Growth sequences have been recorded for Al, Ag, An, Ni, 80/20 Ni/Fe, Fe, and Ge. The growth characteristics are discussed and correlated with observations by electron microscopy. Attention is given to the interpretation of electron-diffraction patterns from very thin films and from (so-called) amorphous films.