We present the generalization of the effective oxidation state (EOS) method to assign oxidation states from wave function analysis to solid-state calculations. The scheme is realized in the framework of the Quantum Theory of Atoms in Molecules (QTAIM), and makes use of the atomic overlap matrices (AOM) of the atoms of the unit cell, expressed (whenever possible) in terms of maximally localized Wannier functions (MLWFs). The method is generally applicable to ionic solids or molecular crystals. The performance of the new method is assessed using a chemically diverse set of 40 solids, including simple metal oxides, perovskites, hydrides, and high-pressure systems with unusual bonding patterns.