The temperature coefficient of resistivity (TCR) has been measured for Cu, Ru, Co, and Ir thin films with thicknesses down to 3 nm to assess the dominant electron scattering mechanism in these films. Ru, Co, and Ir show bulk-like TCR values down to 5 nm with some signs of disorder-induced TCR loweringfor 3 nm for Ru and Co. By contrast, Cu shows a considerably larger TCR value than bulk that increases with decreasing thickness. The results are qualitatively consistent with calculations of the TCR within a semiclassical model. Poster presented at the 2019 IEEE International Interconnect Technology Conference