The object of this book is to clarify the whole aspect of the basic problems concerning the elastic stability of of circular cylindrical shells under typical loading conditions. The book deals with buckling, postbuckling and initial postbuckling problems under one of the three fundamental loads, that is, torsion, pressure and compression. The emphases are placed on the accurate analysis and comprehensive numeral results for the buckling problem, experimental verification of the theoretical analysis for the postbuckling problem and clarification of the range of applicability of the perturbation method for the analysis of initial postbuckling behaviors and imperfection sensitivity. The problems under typical combined loads as well as the influence of the contained liquid are also clarified.