Nonlinear dynamical systems (NDS) theory is the study of how complex processes unfold over time and is sometimes known as chaos theory or complexity theory. Perhaps it was one of those experiences in which “You had to be there,” but the early days of NDS in psychology were rife with excitement. There was so much potential for solving old and new problems and transforming the way psychology was studied that everyone present knew it could occupy entire careers. The days of saying, “Here's what chaos and complexity can do!” were gone years ago, however. NDS scholars have embarked on the less glamorous but ultimately more important task of systematic model building and developing an empirical research agenda. We estimate that about 50 books are published each year that are relevant to some aspect of NDS, psychology, and the life sciences, as well as numerous articles in peer-reviewed journals, such as Nonlinear Dynamics, Psychology, and Life Sciences, signifying that the field is moving forward at a rapid pace.

The waterfall of progress creates two dilemmas that we attempt to resolve by composing this book. The first is to answer a simple question: “What should I read first?” The second is how to reconcile the escalating gap between the state of the science in NDS and the average level of awareness of its accomplishments by professionals in psychology.