The First Edition of Dealing with Complexity has gratified us tremendously by its sales and adoption in many courses throughout the English-speaking world. The aim of producing this Second Edition is to develop a volume to be established firmly as the introduction to systems science that will take us into the next millennium. A number of significant changes have been made in updating the book to take into account the following; new developments in systems thinking, our experience of using the text to teach hundreds of undergraduate and masters students, feedback from business and management, and some suggestions from book reviews.