Co-sputtered thin films have been deposited from MoS2 and WSe2 targets in order to investigate the relationships between tribological behavior and film microstructure. The stoichiometries of pure films for the sputtering conditions used, were found to be MoS1.6 and WSe1.5 as measured by wavelength dispersive x-ray analysis. The mechanical properties of the composite films were investigated by pin-on-disk wear testing in 50% relative humidity air as a function of WSe2 concentration. X-ray diffraction measurements indicate that the microstructure is strongly affected by the inclusion of WSe2 and there is a strong correlation between microstructure and tribological performance. X-ray and Raman measurements indicate a large increase in the c axis of the MoS2, which may be due to intercalation. X-ray photoelectron spectroscopy measurements show no evidence that either Se or W chemically substitutes into the MoS2 Structure.