During the past decade or two considerable fundamental information has been acquired on the mechanisms and rates of molecular energy transfer among vibrational, rotational, and electronic states. It is a well-known fact that the rate and even the products of a chemical reaction can be markedly influenced by the degree of internal state excitation of the reactants. Also, it is clear that many of the chemical processes occurring in the upper atmosphere produce atoms or molecules in excited states. It will be the purpose of this paper to review the state of knowledge of energy transfer mechanisms and kinetic rates as it pertains to atmospheric constituents and to attempt to indicate possible important roles of energy transfer in the physics and chemistry of the stratosphere. Some specific examples will include vibrational relaxation of OH and O3, the possible role of atomic species as quenchants, and electronic/vibrational energy transfer processes.