Ionized cluster beams (ICBs) are widely used to deposit metal, semi-conductor, and insulating films. This paper describes the current state of this technology in both fundamental and applications areas. One important ambi-guity in the theory of metal cluster formation is addressed. Rutherford back-scattering is used to measure the extent of any displacement of surface atoms caused by ICBs. The minimal amount of such surface damage is confirmed by the close-to-ideal values measured for Schottky barrier height on an Al/Si interface. Several examples of ICBs are described.