The application of the charge alternation concept to the charge distribution in doubly charged ions of mono- and polycyclic molecules (Figure 1) is described. The charge density in the systems under investigation was determined both by calculations and experiments (13C NMR). The charges are not distributed uniformly over the entire system but appear in an alternating mode. This charge alternation—a basic characteristic of these systems—is a result of maximum donor–acceptor interactions which stabilize the systems. Rules are derived which enable the prediction of the charge distribution in the system without any need for elaborate calculations.