This volume presents the proceedings of a 1986 Advanced Study Institute entitled "Structure/Reactivity and Thermochemistry of Ions," held at Les Arcs, France, June 30 to July 11, 1986. The format of a NATO Institute is ideally suited to in-depth communications between scien- tists of diverse backgrounds. Particularly in the field of ion physics and chemistry, where on-going research involves physicists, physical chemists, and organic chemists - who use a variety of experimental and theoretical techniques - it is found that in the relaxed but stimula- ting atmosphere of a NATO ASI, each...