Adding another volume, even if only a slim one, to the technical books already published requires some justification. Mine is, firstly, that plate theory is not well represented in the available elementary texts, and secondly that no existing text adequately covers modern applications. The present account is intended to be elementary (though this is a relative term) while still providing stimulation and worthwhile experience for the reader. Special features of interest will I hope be the treatment of geometry of surfaces and the attempts around the end of the work to speculate a little. The detailed treatment of geometry of surfaces has been placed in an appendix where it can readily be referred to by the reader. My interest in plate theory extends back many years to the energetic and stimulating discussions with my supervisor, Professor R. W. Tiffen, at Birkbeck College, London, and a debt to him remains. Interest was rekindled for me by Dr R. E. Melchers when I supervised him in Cambridge some ten years ago, and more recently my stay at Strathclyde University and encouragement and stimulation in the Civil Engineering Department led me to undertake the present work. The typescript was prepared by Ms Catherine Drummond and I thank her warmly for this and other assistance, always cheerfully offered. My thanks also to the publishers and the referees for useful comments and advice. P.G.L.