Sulfur K-edge X-ray absorption spectroscopy (XAS) of anhydrous CuSO4 reveals a well-resolved preedge transition feature at 2478.8 eV that has no counterpart in the XAS spectra of anhydrous ZnSO4 or copper sulfate pentahydrate. Similar but weaker preedge features occur in the sulfur K-edge XAS spectra of [Cu(itao)SO4] (2478.4 eV) and [Cu{(CH3)(6)tren}SO4] (2477.7 eV). Preedge features in the XAS spectra of transition metal ligands are generally attributed to covalent delocalization of a metal d-orbital hole into a ligand-based orbital. Copper L-edge XAS of CuSO4 revealed that 56% of the Cu(II) 3d hole is delocalized onto the sulfate ligand. Hybrid density functional calculations on the two most realistic models of the covalent delocalization pathways in CuSO4 indicate about 50% electron delocalization onto the sulfate oxygen-based 2p orbitals; however, at most 14% of that can be found on sulfate sulfur. Both experimental and computational results indicated that the high covalence of anhydrous CuSO4 has made sulfate more like the radical monoanion, inducing an extensive mixing and redistribution of sulfur 3p-based unoccupied orbitals to lower energy in comparison to sulfate in ZnSO4. It is this redistribution, rather than a direct covalent interaction between Cu(II) and sulfur, that is the origin of the observed sulfur XAS preedge feature. From pseudo-Voigt fits to the CuSO4 Sulfur K-edge XAS spectrum, a ground-state 3p character of 6% was quantified for the orbital contributing to the preedge transition, in reasonable agreement with the DFT calculation. Similar XAS fits indicated 2% sulfur 3p character for the preedge transition orbitals in [Cu(itao)SO4] and [Cu{(CH3)(6)tren}SO4]. The covalent radicalization of ligands similar to sulfate, with consequent energy redistribution of the virtual orbitals, represents a new mechanism for the induction of ligand preedge XAS features. The high covalence of the Cu sites in CuSO4 was found to be similar to that of Cu sites in oxidized cupredoxins, including its anistropic nature, and can serve as the simplest inorganic examples of intramolecular electron-transfer processes.