Measurements were made of thermal radiation from the shock layer about small gun-launched models flying either in still air or upstream through the test section of a shock-tube-driven hypersonic wind tunnel. Total velocities ranged up to 12.4 km/sec. Current knowledge of shock-layer radiation is evaluated by comparing the results with available predictions of equilibrium radiation and with shock-tube measurements of nonequilibrium radiation. Scaling rules and methods for predictive radiative heating of full-scale vehicles are discussed.