On the basis of the principle of electronegativity equalization and density-functional theory, an atom-bond electronegativity equalization method has been developed for the calculation of the charge distribution in large molecules that are connectivity and geometry dependent. The effective electronegativities of an atom and a bond in a molecule are derived and given by equations that contain respective electronegativities, hardness terms, and contributions that come from other atomic and bond charges. The parameters A, B, C, and D are the valence-state electronegativity and the valence-state hardnesses. They are obtained by calibrating through calculations of more than 100 model molecules and are transferable and consistently usable. The atom-bond electronegativity equalization method is tested through calculation of the charge distributions in several large organic molecules, It has been shown that there is a very good agreement between the results obtained by the atom-bond electronegativity equalization method and those obtained by the corresponding ab initio quantum chemical calculations.