A tutorial review by Prof. Yi Zhao and Prof. Wanzhen Liang has been published in Chem. Soc. Rev. Chem. Soc. Rev. (2012, 41, 1075-1087), which summarizes the rate theories for charge transfer and separation in organic solar cells. Starting from the Fermi’s golden rule for weak electronic coupling, we display the microcanonical and canonical rates. The ?uctuation e?ect of bridges on the rate is further emphasized. Then, several rate approaches beyond the perturbation limit are revealed. Finally, we discuss the electronic structure theory for the calculations of electronic coupling and reorganization energy that are two key parameters in charge transfer, and show several applications.