At molecular level, the electronic excitation energy or charge of one molecule can be transferred to others with a unique rate constant. How to understand and derive such rate constant is a very important subject in theoretical chemistry. Two most well known theories in these fields of research are Foster theory and Marcus theory. The former describes the transfer of the electronic excitation energy through resonance interactions between two transition dipoles, and the latter explains how the charge transfer occurs between two atoms or molecules solvated in dielectric media. The impacts of these seminal theories on the progress of physical chemistry have been great. However, many of modern experimental and computational results also indicate the need for further developments and refinements of these theories, and there are now active communities of theoretical chemists devoted to these efforts. In recent years, I made significant contributions to these fields by generalizing Forster theory to nonequilibrium and multichromophoric cases, and by extending Marcus theory to the cases with significant non-Condon effects due to torsional quantum modes. Current research is focused on resolving remaining theoretical challenges such as understanding the role of quantum coherence and the non-Condon effects in more general situations.