Rydberg Series in Atoms and Molecules deals with the Rydberg states of atomic and molecular systems. Rydberg series in atomic spectra and of diatomic molecules are examined, along with Rydberg terms of polyatomic molecules such as hydrocarbons with triple bonds, hydrocarbon molecules with double bonds, and benzene and benzene derivatives. Comprised of four chapters, this book begins with an overview of the spectrum of the hydrogen atom, along with some elementary and useful concepts and definitions. Some difficulties in the classification of excited states of simple molecules into Rydberg and non-Rydberg states are highlighted. The next chapter considers Rydberg series in atomic spectra and theoretical methods for quantitative description of atomic structures. One-electron models for Rydberg terms are also described, together with Rydberg series of diatomic molecules such as N2 and O2, CO and NO, and bromine and iodine. The final chapter is devoted to Rydberg terms of polyatomic molecules including hydrocarbons with triple and double bonds; benzene and benzene derivatives; hydrides with central atom; saturated hydrocarbons; and aldehydes and ketones. This monograph is written primarily for both students and nonspecialists.