We present the first x-ray Thomson scattering measurements of temperature and density from spherically imploding matter. The shape of the Compton down-scattered spectrum provides a first principles measurement of the electron velocity distribution function, dependent on Te and the Fermi temperature TF̃ ne2/3. In-flight compressions of Be and CH targets reach 6-13 times solid density, with Te/TF ~ 0.4-0.7, resulting in minimum adiabats of ~1.6-2. These measurements indicate the ability for single shot characterization of matter at extreme densities, e.g. relevant for the National Ignition Facility (NIF).