The nuclear spin-lattice relaxation time of superconducting aluminum has been measured from 0.35°K to the critical temperature. The method used was that of Hebel and Slichter; low temperatures were attained through the use of a helium-three cryostat. The estimated energy gap is 3.2 kTc, in agreement with microwave measurements. The data are in good agreement with the predictions of Hebel and Slichter based on the Bardeen, Cooper, and Schrieffer theory of superconductivity. The data indicate a smearing or width of the BCS energy levels which decreases with increasing temperature and is approximately 110 of the energy gap at all temperatures.