In this study, we employed continuous microscratch testing to determine the effects of interface roughness on adhesion and fracture toughness of thin Ta2N films. These films were sputterdeposited on single crystal sapphire and polycrystal alumina substrates to a thickness of 0.5 μm. Comparison of the results showed that the interfacial fracture energy increased from 0.4 J/m2 for films on the single crystals to 1.5 J/m2 for films on the polycrystals with a corresponding increase in fracture toughness values. These results are consistent with crack deflection and interface roughness models and are useful for understanding adhesion and toughness on the submicron scale. The results also show that the continuous microscratch technique is a viable approach to determining adhesion and toughness of bi-material systems.