The first experimental determination of the chemical shielding tenser of a singlet carbene center, 1,3,4,5-tetramethylimidazol-2-ylidene (1), is reported. Detailed ab initio theoretical calculations of the chemical shielding tensors are reported for local density functional theory (LDFT) and the Hartree-Fock levels (HF) in the LORG and IGLO frameworks. The chemical shielding anisotropy is quite large, which is characteristic of the lowest-energy-singlet carbene centers. The anisotropy at the carbene center in 1 is similar to 240 ppm. This is one of the largest anisotropies observed for carbon in a strictly organic framework. The calculations indicate that the orientation of the chemical shielding tensor of the carbene is such that the most shielded;component is perpendicular to the molecular plane, with the intermediate component oriented approximately along the direction of the lone pair, and the least shielded component perpendicular to the other two. This orientation, as well as the relative size of the anisotropy, agrees with calculations on the singlet carbenes 1, imidazol-2-ylidene (2), and :CF2. The size of the anisotropy is predicted to be enhanced for the parent carbene :CH2.