The growth of Fe films on ZnSe(001) epilayers and bulk GaAs(001) substrates has been studied to determine the mode of film growth, the formation of the interface, and the structure of the overlayer at the 1–10 monolayer level. Auger electron diffraction (AED), x‐ray photoelectron spectroscopy (XPS), and reflection high‐energy electron diffraction data are obtained for incremental deposition of the Fe(001) overlayer. The coverage dependence of the AED forward scattering peaks reveals a predominantly layer‐by‐layer mode of film growth at 175 °C on ZnSe, while a more three‐dimensional growth mode occurs on the oxide‐desorbed GaAs(001) substrate. XPS studies of the semiconductor 3dlevels indicate that the Fe/ZnSe interface is less reactive than the Fe/GaAs interface.