This book presents a new mindset for teacher learning and educational change. When viewed from a conventional mechanistic paradigm, educational change is a linear step-by-step process that is supported by a simplistic approach to teacher learning. Although this approach often produces disappointing results, rarely is an alternative one proposed. What is new in this book is that educational change and teacher learning are viewed from a paradigm based on complexity theory, assuming that change is a nonlinear process that needs to be supported by a framework for long-term teacher learning. The central question of this book, therefore, is 'What conditions will help to establish a framework for long-term teacher learning to support educational change?' To address this question, a systems thinking approach is used to draw together ideas from existing learning perspectives into a new theoretical framework called a Professional Learning System. This framework is not a formula, but a new mindset to help us understand the nonlinear dynamics of educational change and teacher learning.