This book is a commemorative volume celebrating the 65th birthday of Professor Demeter Krupka, one of the founders of the modern geometrical theory of the calculus of variations, and a major contributor to the topic over the past 35 years. The book is a collection of survey articles on the theory and on its applications in analysis, geometry and physics. The articles contain a variety of important results, techniques and applications that would normally be found only in the original papers scattered among a number of different journals. The authors, listed below, all have established reputations in this field: Book jacket.