The relative merits of time-temperature superposition procedures (those of Leaderman, Tobolsky, Ferry, Kě, McCrum, and Morris) have been assessed for the glass-rubber (a) relaxation of an epoxy resin. Measurements of creep compliance in shear were made at temperatures between 24° and 190°C. The different superposition procedures yield shift factor versus temperature plots which are essentially identical. Differences between the procedures are greatest in the master curves particularly at short and at long times. The McCrum-Morris procedure alone yielded a smooth master curve at all times. At temperatures above the glass transition the shift factor versus temperature plots followed the WLF equation.