In the last decade or so the theory of shells has undergone a tremendous increase in development. Formerly a subject of interest only to a few special- ists and for which the literature was relatively smalI, the needs of structures for aerospace missions instigated a torrent of papers on all facets of the theory which also found application in the less glamorous earthbound shell struc- tures important in everyday life. Some idea of the rapidity of the development can be gained from the fact that a bibliography* completed in 1953 listed some 1455 books and papers as the sum total ofthe literature on shell theory to that date. Three years later, however, a supplementt added another 884 papers to the list, an increase of 60 per cent in that short period of time. The number of papers published since these listings has increased to an extent that does not bear contemplation. Obviously no single volume could contain all that constitutes the theory of shells and so this book is restricted to that portion of the theory associated with small deformations of elastic shells. Plastic deformations of shells, which is hardly developed, and nonlinear deformations and stability, which would require at least aseparate volume, are thus excluded. Even with this restriction, however, the present volume represents a long overdue compro- mise between completeness and finiteness. In making this compromise I have undoubtedly omitted discussions of many topics and references to many excellent papers which should have been included.