A balanced and comprehensive account is given here of the electron-atom-molecule scattering calculations carried out by the author. The topic is of great interest owing to many-fold relevance e.g. in the planetary and outer space environments. Collisions of electrons with atoms and molecules provide a unique diagnostic probe of the fundamental interactions of atomic-molecular systems and are the basic physical processes that determine the behavior of ionized gases. To understand and to predict quantitatively the behavior of ionized gases found in planetary environments etc, requires development of theory of electron collisions along with mathematical and computational tools that enable reliable calculations of the different collision parameters. The present book signifies our sincere efforts towards electron-atom-molecule scattering: theory and scattering cross section calculations. The derived scattering cross sections can be utilized to carry out variety of parameters. The applications of these cross sections in the planetary atmospheres and outer space environments have been discussed in the next volume of this book series.