This volume gives and excellent survey of our present knowledge of molecularprocesses in stellar and proto-stellar objects. It reviews molecular physicsin stellar environments and is intended to bridge the gap between astrophysicists and chemists. The topics range from the theoretical to the computational and include observational data. Among the topics treated are questions of stellar evolution, the determination of physical propertiesand structures , and the chemical composition of stellar protospheres. Opacity is studied in the context of various types of stellar and proto-stellar objects.