Monte Carlo models of crystal growth have contributed to the theoretical understanding of thin film deposition, and are now becoming available as tools to assist in device fabrication. Because they combine efficient computation and atomic-level detail, these models can be applied to a large number of crystallization phenomena. They have played a central role in the understanding of the surface roughening transition and its effect on crystal growth kinetics. Ln addition, columnar growth, vacancy and impurity trapping, and other growth phenomena that are closely related to atomic-level structure have been investigated by these simulations. in this chapter we review some of these applications and discuss MC modeling of sputter deposition based on materials parameters derived from first principles and molecular dynamics methods. We discuss models of deposition which include the atomic scale, but can also simulate film structure evolution on time scales of the order of hours. By the use of advanced computers and algorithms, we can now simulate systems large enough to exhibit clustered, columnar, and polycrystalline film structures. The event distribution is determined from molecular dynamics simulations, which can give diffusion rates, defect production, sputtering yields, and other information needed to match real materials. We discuss simulations of deposition into small vias and trenches, and their extension to the length scale of real devices through scaling relations.