The authors have written a rigorous yet elementary and self-contained book to present, in a unified framework, generalized convex functions, which are the many non-convex functions that share at least one of the valuable properties of convex functions and which are often more suitable for describing real-world problems. The book will be a useful tool not only for researchers, but also for graduates and advanced students working in economics, mathematical programming, the management sciences and operations research. It begins with a review of convex analysis and the fundamental theoretical findings on generalized convexity and on optimization, including their applications. The text continues with an introductory chapter devoted to generalized monotonicity and its relationship to generalized convexity, with the characterizations of important classes of fractional programming, and with theoretical properties and sequential methods. The book also includes numerous exercises and two appendices which list the findings consulted.