The world consists of many complex systems, ranging from our own bodies to ecosystems to economi~ systems. Despite their diversity, complex systems have many structural and functional features in common that can be effec­ tively simulated using powerful, user-friendly software. As a result, virtually anyone can explore the nature of complex systems and their dynamical be­ havior under a range of assumptions and conditions. This ability to model dy­ namic systems is already having a powerful influence on teaching and study­ ing complexity. The books is this series will promote this revolution in "systems thinking" by integrating skills of numeracy and techniques of dynamic modeling into a variety of disciplines. The unifying theme across the series will be the power and simplicity of the model-building process, and all books are designed to engage the reader in developing their own models for exploration of the dy­ namics of systems that are of interest to them. Modeling Dynamic Systemsdoes not endorse any particular modeling par­ adigm or software. Rather, the volumes in the series will emphasize simplic­ ity of learning, expressive power, and the speed of execution as priorities that will facilitate deeper system understanding.