Abstract
Hubble Space Telescope (HST) observations of young supernova remnants offer exquisite spatial resolution and access to ultraviolet wavelengths for imaging and spectroscopic investigations. I highlight recent HST studies that isolate uncontaminated ejecta knots and filaments for studying post-shock cooling regions and the development of instabilities, and determining elemental abundances in the fast-moving supernova debris. I summarize results for Cas A in the Galaxy, N 132D and SNR 0540-69.3 in the Large Magellanic Cloud, and 1E 0102.2-7219 in the Small Magellanic Cloud.
