The present volume "Field Theory, Quantum Gravity and " "Strings, II" comprises for the lectures delivered in 1985/86 at a joint seminar of the DAPHE observatory at Meudon and the LPTHE University Paris VI. This set of lectures contains selected topics of current interest in field and particle theory, cosmology and statistical mechanics. Basic problems of string and superstring theory are treated in a contemporary perspective, and quantum field theoretical as well as string approaches to cosmology are presented. Recent progress on integrable theories and related subjects in two, four and more dimensions is reviewed. This seminar on current developments in mathematical physics addresses researchers as well as graduate students.