This monograph covers a broad spectrum of topics in the very broad field of gas phase molecular collision dynamics. The Introduction previews each of the four fol lowing topics and attempts to sew them together with a common thread. In addition, a brief review of quantum reactive scattering is given there along with some gen eral remarks which highlight the difficulties in doing quantum reactive scatter ing calculations. The chapters are all written by theoreticians who are, of course, experts in the subjects they have written about. Three chapters, the ones by Secrest, Schatz, and the one by...