Emerging classes of ultrahigh temperature materials hold tremendous potential for use as structural materials that can operate in the extreme environments required for next generation, space access, civil transport, and power generation. Realization of components and systems that can operate at extreme temperatures will require detailed understanding of the elastic, plastic, and thermal response of materials at salient temperatures and environments. The recent development of subscale tensile experiments that employ Joule and conduction heating, ultrahigh temperature ultra-violet digital image correlation (UV-DIC), and multi-spectral pyrometry is providing a pathway for measuring thermal and elastic properties up to the melting point, measurement of ultrahigh temperature tensile strengths, and opening a window for clarifying and understanding plastic deformation mechanisms that govern mechanical behavior as temperatures approach 2,000°C.