The mechanical properties of thin-film Cu/Cu-Ni and Cu/Ag multilayers are examined in this study. Films were prepared by magnetron sputter deposition onto cleaved NaCl substrates. The use of a computer-controlled deposition system enabled the multilayer interface width to be varied, as well as the multilayer amplitude and bilayer thickness. The Cu/Cu-Ni multilayers had the form of (001) oriented single crystal films, but for Cu-Ag multilayers only polycrystalline films could be obtained in the (001) orientation. For Cu/Cu-15%Ni multilayers, the tensile strengths were measured and observed to increase with decreasing interface width at constant wavelength. Tensile strengths were also found to increase with increasing composition modulation amplitude. For films with constant interface width but bilayer thicknesses ranging from 10 to 60 nm, the tensile strength was relatively constant. The results are consistent with previous theoretical treatments, particularly the theory of modulus hardening.