This is the substantially updated second edition of the first comprehensive overview of systems science for advanced undergraduate and graduate students. This new edition adds supplemental examples and exercises, and a selection of recent papers in systems science. From a review in Kybernetika: "One is struck in reading Facets at just how monumental of an undertaking this ... As Klir presents it, systems science represents a new dimension of science. ... I would like to suggest that a close study of Facets is likely to benefit anyone interested in gaining new insights into scientific inquiry itself as well as new methods for investigating problems of individual interest. Thanks Professor Klir!"--Richard M. Smith.