Small particles and film surfaces are studied using high resolution electron microscopy under ultrahigh vacuum conditions, coupled with analyses using theoretical modeling and simulation. The small particle research emphasizes experimental analysis of quasi-molten behavior of nanoparticles employing a systematic examination of real-time structural evolution. The surface research examines surface reconstructions in thin films. Plan view imaging of surfaces in transmission electra microscopy focusses on the interaction of bulk defects with surface reconstructions in gold and iridium. Critical to the research is the application of ultrahigh vacuum environments to maintain surfaces free of contamination. %%% The properties of nanoparticles and thin film surfaces depend in part on their surface structures. This research explores the use of high resolution electron microscopy to quantitatively describe the atomic arrangements on the surfaces of small particles and thin films.