The initial stages of Cu growth (up to 20 Angstrom) on ordered Al2O3 ultrathin films (similar to 20 Angstrom thick) synthesized on a Re(0001) substrate are studied by low-energy ion scattering (LEIS) and x-ray photoelectron spectroscopy (XPS). LEIS results indicate that Cu grows as three-dimensional clusters on the Al2O3 films at both 80 and 300 K. XPS results show decreases in the Cu 2p(3/2) binding energy and increases in the Cu L(3)M(4,5)M(4,5) kinetic energy as a function of coverage. Analysis of these results indicates that Cu is not oxidized at the interface. For the coverage-dependent shifts in the Cu 2p(3/2) peaks, the initial-state and final-state contributions and their relation to Cu cluster size are discussed.