This book is a revised and updated version of the INFORMS award winner for `best dissertation on Location Analysis of 1995'. The book integrates two seemingly unrelated fields: location analysis and fractional programming. Location analysis deals with the problem of where to locate facilities in such a way as to optimize a particular criterion taking into account the existing clients. Fractional programming is a special field of nonlinear programming dealing with optimization problems where the objective function consists of a ratio of given functions. Although the application scope of fractional programming is vast, it has not been much related to specific operations-research problems, and in particular, to location analysis. This book manages to bridge this gap by tackling several location models that require combined solution techniques and theoretical results from both fields. Those interested in location theory will find not only new results in discrete location, especially in two-level location models, but also the theoretical and practical potential of fractional programming in location theory. Those in the field of fractional programming will find a clear and econometrical interpretation of the basic techniques of fractional and generalized fractional programming and new theoretical duality results that lead to efficient and innovative algorithms. Audience: Researchers in mathematics, operations research and management science interested in combinatorial optimization, fractional programming, and location theory.