Three forms of crystalline aspartame have been observed: two hemihydrate polymorphs and a dihemihydrate. The C-13 CP/MAS NMR spectra of two of the forms of aspartame showed that certain carbons have up to three resonances due to different conformations/arrangements of molecules in the asymmetric unit cell. Techniques for assigning resonances based upon the number of attached protons or J couplings were not effective because the multiple resonances arise from the same carbon in the molecule. We used two-dimensional exchange experiments on uniformly C-13-labeled aspartame to assign the spectra of aspartame. Experiments performed with typical MAS rates (7 kHz) and H-1 decoupling powers (63 kHz) of uniformly C-13-labeled aspartame were uninformative because H-1-C-13 and C-13-C-13 dipolar couplings significantly broadened these resonances. Increasing the spinning rate to 28 kHz and the H-1 decoupling power to 263 kHz increased the resolution sufficiently to observe crystallographically inequivalent sites. Two-dimensional radio frequency driven dipolar recoupling (RFDR) and exchange experiments using very high spinning speed and decoupling power gave complimentary assignment information for short (1-2 bond) and long (>3 bonds) range interactions in the two polymorphic forms. For one form of aspartame, peaks were assigned to aspartame molecules in three inequivalent crystalline environments.