This book offers a multidisciplinary approach to systems theory, investigating its general principles, mathematical models, and applications in health sciences. It describes how leaders in the field have made a transition from equations and models to dilemmas faced in the real world. This book is meant to simplify our understanding of disparate hierarchical and complex open systems in the world by making us aware of patterns of action among its components. These interactions lead to cascading effects within the system which end up changing it as a whole. This self-organization often leads to unpredictable results transforming the system, or integrating the same, into a still more complex system. These results, not necessarily the ones originally sought by their organizers, may offer the system the best opportunity for sustainable and adaptive growth. In the end, readers of this book will gain a basic understanding of systems theory, its application to natural and manmade processes, and how systems grow and equilibrate with their environment in order to continue functioning.