Combined surface science and high-energy ion beam techniques have been used to characterize the composition, structure, and thermal stability of Ag layers <900 Å thick on Cu(110). A uniform Ag/Cu surface composite is formed for one-monolayer coverage. Analysis of its growth with low-energy electron diffraction shows that the Ag is initially confined to the [11̄0] troughs and that further deposition results in a Ag(111) layer exhibiting c(2×4) symmetry. This determination of Ag coverage is consistent with absolute coverages measured with Rutherford backscattering. Beyond one-monolayer coverage, the deposition of Ag at 300 K produces clustering (Stranski–Krastanov mechanism) in contrast to a poorly ordered but more uniform layering mode when deposited at 130 K. Following nucleation for a deposition between one and two monolayers at 300 K, Ag clusters ∼20 Å thick grow laterally across the surface up to five- or six-monolayers deposition. Continuous films grown cold at thicknesses ≤115 Å are found to agglomerate above 500 K exposing a tenacious Ag–Cu interface like that formed by one-monolayer Ag deposition.