We present evidence that it is the presence or absence of atomic terraces with a specific crystallographic orientation on the (102) Al2O3 surface that promotes growth of single-crystal (001) CeO2 films over polycrystalline (111) CeO2 films. The CeO2 film nucleates so that the [010] and [100] directions of the film align parallel and perpendicular to the terrace edges. In the absence of terraces, multidomain (111) CeO2 films result in which the in-plane orientation of the two domains are rotated by 85.71°, so that a [110] CeO2 direction aligns parallel to either the $$ \left[ {\bar{2}21} \right] $$ or $$ \left[ {\bar{2}\bar{4}1} \right] $$ Al2O3 direction.