This book is the result of a collaboration between a number of authors working as a European Brief Therapy Association (EBTA) task-group. This is the 2020 state of the art version of understanding and learning Solution-Focused Practice. It is applicable to various fields of practice, such as therapy, coaching, supervision, social change, educational work, leadership, and other contexts where a detailed understanding of how to manage and promote change in social systems and communities is intended. The book presents a coherent theory of solution-focused practice for those who want to understand the rationale, together with a comprehensive description of solution-focused practice that can be used in daily practice or training and for developmental purposes. Theory here is defined as a process theory describing how the solution-focused practice is done, together with explanations of how and why the change process is initiated. This book is also a statement of what solution-focused practice is and what are the sound reasons to use it.