The fundamental deformation and fracture processes of thin metallic films with a nanograined microstructure and of thin hard coatings with a composite nanocrystalline- amorphous structure will be investigated by using the in situ TEM straining technique. For the nanograined materials, a novel uniaxial tensile test device has been fabricated using microelectronic fabrication processes to integrate MEMS force sensors with metallic films on a silicon wafer. The device permits direct correlation of the measured mechanical properties with the observed deformation mechanisms. The importance of grain boundaries as sources and sinks for dislocations will be demonstrated for a 200-nanometer thick freestanding aluminum film. For the hard coatings, a TiC coating supported on a stainless steel substrate was fabricated. Preliminary results suggest that the failure mode for coatings with the same C/Ti ratio is dependent on the percentage of crystalline TiC and the oxygen content, demonstrating the importance optimizing the composition and structure. Results from these studies will be compared with model predictions.